flatten Login struct

The current Login structure is nested:

```
Login {
  RecordFields record;
  LoginFields fields;
  SecureLoginFields sec_fields;
}
```

and thus exposes internal data structuring to the consumer. Since we make the encryption transparent for the consumer (Android, iOS, desktop) here, such a separation no longer makes sense here and above can be simplified to

```
Login {
    // record fields
    string id;
    i64 times_used;
    i64 time_created;
    i64 time_last_used;
    i64 time_password_changed;

    // login fields
    string origin;
    string? http_realm;
    string? form_action_origin;
    string username_field;
    string password_field;

    // secure login fields
    string password;
    string username;
}
```

The advantage of eliminating this separation lies, on the one hand, in the simplification of the API and the resulting easier use of the component, and on the other hand, in the easier changeability of the internal data structure. If, for example, we decide later to encrypt additional fields, such a change is possible without having to adapt the consumers.

components/logins/android/src/test/java/mozilla/appservices/logins/DatabaseLoginsStorageTest.kt

@@ -46,33 +46,25 @@ class DatabaseLoginsStorageTest {
 
         store.add(
             LoginEntry(
-                fields = LoginFields(
-                    origin = "https://www.example.com",
-                    httpRealm = "Something",
-                    usernameField = "users_name",
-                    passwordField = "users_password",
-                    formActionOrigin = null,
-                ),
-                secFields = SecureLoginFields(
-                    username = "Foobar2000",
-                    password = "hunter2",
-                ),
+                origin = "https://www.example.com",
+                httpRealm = "Something",
+                usernameField = "users_name",
+                passwordField = "users_password",
+                formActionOrigin = null,
+                username = "Foobar2000",
+                password = "hunter2",
             ),
         )
 
         store.add(
             LoginEntry(
-                fields = LoginFields(
-                    origin = "https://www.example.org",
-                    httpRealm = "",
-                    formActionOrigin = "https://www.example.org/login",
-                    usernameField = "users_name",
-                    passwordField = "users_password",
-                ),
-                secFields = SecureLoginFields(
-                    password = "MyVeryCoolPassword",
-                    username = "Foobar2000",
-                ),
+                origin = "https://www.example.org",
+                httpRealm = "",
+                formActionOrigin = "https://www.example.org/login",
+                usernameField = "users_name",
+                passwordField = "users_password",
+                password = "MyVeryCoolPassword",
+                username = "Foobar2000",
             ),
         )
 
@@ -93,17 +85,13 @@ class DatabaseLoginsStorageTest {
 
         val login = store.add(
             LoginEntry(
-                fields = LoginFields(
-                    origin = "https://www.example.com",
-                    httpRealm = "Something",
-                    usernameField = "users_name",
-                    passwordField = "users_password",
-                    formActionOrigin = null,
-                ),
-                secFields = SecureLoginFields(
-                    username = "Foobar2000",
-                    password = "hunter2",
-                ),
+                origin = "https://www.example.com",
+                httpRealm = "Something",
+                usernameField = "users_name",
+                passwordField = "users_password",
+                formActionOrigin = null,
+                username = "Foobar2000",
+                password = "hunter2",
             ),
         )
 
@@ -112,17 +100,13 @@ class DatabaseLoginsStorageTest {
 
         // N.B. this is invalid due to `formActionOrigin` being an invalid url.
         val invalid = LoginEntry(
-            fields = LoginFields(
-                origin = "https://test.example.com",
-                formActionOrigin = "not a url",
-                httpRealm = "",
-                usernameField = "users_name",
-                passwordField = "users_password",
-            ),
-            secFields = SecureLoginFields(
-                username = "Foobar2000",
-                password = "hunter2",
-            ),
+            origin = "https://test.example.com",
+            formActionOrigin = "not a url",
+            httpRealm = "",
+            usernameField = "users_name",
+            passwordField = "users_password",
+            username = "Foobar2000",
+            password = "hunter2",
         )
 
         try {
@@ -138,8 +122,8 @@ class DatabaseLoginsStorageTest {
         assertNull(LoginsStoreMetrics.readQueryCount.testGetValue())
         assertNull(LoginsStoreMetrics.readQueryErrorCount["storage_error"].testGetValue())
 
-        val record = store.get(login.record.id)!!
-        assertEquals(record.fields.origin, "https://www.example.com")
+        val record = store.get(login.id)!!
+        assertEquals(record.origin, "https://www.example.com")
 
         assertEquals(LoginsStoreMetrics.readQueryCount.testGetValue(), 1)
         assertNull(LoginsStoreMetrics.readQueryErrorCount["storage_error"].testGetValue())
@@ -153,13 +137,13 @@ class DatabaseLoginsStorageTest {
         val login = store.list()[0]
         // Wait 100ms so that touch is certain to change timeLastUsed.
         Thread.sleep(100)
-        store.touch(login.record.id)
+        store.touch(login.id)
 
-        val updatedLogin = store.get(login.record.id)
+        val updatedLogin = store.get(login.id)
 
         assertNotNull(updatedLogin)
-        assertEquals(login.record.timesUsed + 1, updatedLogin!!.record.timesUsed)
-        assert(updatedLogin.record.timeLastUsed > login.record.timeLastUsed)
+        assertEquals(login.timesUsed + 1, updatedLogin!!.timesUsed)
+        assert(updatedLogin.timeLastUsed > login.timeLastUsed)
 
         assertThrows(LoginsApiException.NoSuchRecord::class.java) { store.touch("abcdabcdabcd") }
 
@@ -171,11 +155,11 @@ class DatabaseLoginsStorageTest {
         val store = getTestStore()
         val login = store.list()[0]
 
-        assertNotNull(store.get(login.record.id))
-        assertTrue(store.delete(login.record.id))
-        assertNull(store.get(login.record.id))
-        assertFalse(store.delete(login.record.id))
-        assertNull(store.get(login.record.id))
+        assertNotNull(store.get(login.id))
+        assertTrue(store.delete(login.id))
+        assertNull(store.get(login.id))
+        assertFalse(store.delete(login.id))
+        assertNull(store.get(login.id))
 
         finishAndClose(store)
     }
@@ -189,8 +173,8 @@ class DatabaseLoginsStorageTest {
         test.wipeLocal()
         assertEquals(0, test.list().size)
 
-        assertNull(test.get(logins[0].record.id))
-        assertNull(test.get(logins[1].record.id))
+        assertNull(test.get(logins[0].id))
+        assertNull(test.get(logins[1].id))
 
         finishAndClose(test)
     }