chore: migrate to expecttype eslint rules

This migrates to using an eslint plugin for `$ExpectType` and friends so
we can do it as part of the lint script.

For now, `typescript` had to be added to the root project since the rxjs
site is still on an older typescript which confuses eslint (since it
ends up being hoisted by yarn).

package.json

@@ -25,6 +25,7 @@
   "dependencies": {},
   "devDependencies": {
     "@nx/js": "17.2.6",
-    "nx": "17.2.6"
+    "nx": "17.2.6",
+    "typescript": "~4.9.4"
   }
 }

packages/rxjs/package.json

@@ -74,7 +74,6 @@
   "scripts": {
     "changelog": "npx conventional-changelog-cli -p angular -i CHANGELOG.md -s",
     "lint": "eslint --ext=ts,js src spec spec-dtslint",
-    "dtslint": "npm run lint && tsc -b ./src/tsconfig.types.json",
     "test": "yarn build && cross-env TS_NODE_PROJECT=tsconfig.mocha.json mocha --config spec/support/.mocharc.js \"spec/**/*-spec.ts\"",
     "test:esm": "node spec/module-test-spec.mjs",
     "test:circular": "dependency-cruiser --validate .dependency-cruiser.json -x \"^node_modules\" dist/esm",
@@ -83,7 +82,6 @@
     "build:clean": "shx rm -rf ./dist",
     "build": "yarn build:clean && yarn compile && node ./tools/generate-alias.js",
     "watch": "nodemon -w \"src/\" -w \"spec/\" -e ts -x npm test",
-    "watch:dtslint": "nodemon -w \"src/\" -w \"spec-dtslint/\" -e ts -x yarn dtslint",
     "copy_common_package_files": "node ../../scripts/copy-common-package-files.js"
   },
   "repository": {
@@ -143,15 +141,16 @@
     "@types/shelljs": "^0.8.8",
     "@types/sinon": "^10.0.13",
     "@types/sinon-chai": "^3.2.9",
-    "@typescript-eslint/eslint-plugin": "^6.9.0",
-    "@typescript-eslint/parser": "^6.9.0",
+    "@typescript-eslint/eslint-plugin": "^6.16.0",
+    "@typescript-eslint/parser": "^6.16.0",
     "chai": "^4.3.7",
     "color": "3.0.0",
     "colors": "1.1.2",
     "cross-env": "5.1.3",
     "cz-conventional-changelog": "1.2.0",
     "dependency-cruiser": "^9.12.0",
     "eslint": "^8.52.0",
+    "eslint-plugin-expect-type": "^0.3.0",
     "form-data": "^3.0.0",
     "fs-extra": "^8.1.0",
     "husky": "^4.2.5",

packages/rxjs/spec-dtslint/.eslintrc.json

@@ -0,0 +1,8 @@
+{
+  "extends": [
+    "plugin:expect-type/recommended"
+  ],
+  "plugins": [
+    "expect-type"
+  ]
+}

packages/rxjs/spec-dtslint/firstValueFrom-spec.ts

@@ -1,5 +1,5 @@
 import { firstValueFrom } from 'rxjs';
-import { a$ } from 'helpers';
+import { a$ } from './helpers';
 
 describe('firstValueFrom', () => {
   it('should infer the element type', () => {

packages/rxjs/spec-dtslint/lastValueFrom-spec.ts

@@ -1,5 +1,5 @@
 import { lastValueFrom } from 'rxjs';
-import { a$ } from 'helpers';
+import { a$ } from './helpers';
 
 describe('lastValueFrom', () => {
   it('should infer the element type', () => {

packages/rxjs/spec-dtslint/observables/forkJoin-spec.ts

@@ -1,4 +1,4 @@
-import { a$, b$, c$ } from 'helpers';
+import { a$, b$, c$ } from '../helpers';
 import { of, forkJoin } from 'rxjs';
 
 describe('deprecated rest args', () => {

packages/rxjs/spec-dtslint/observables/iif-spec.ts

@@ -1,4 +1,4 @@
-import { a$, b$ } from 'helpers';
+import { a$, b$ } from '../helpers';
 import { iif, EMPTY } from 'rxjs';
 
 const randomBoolean = () => Math.random() > 0.5;
@@ -31,4 +31,4 @@ it('should support inference from a predicate that returns any', () => {
   }
 
   const o$ = iif(alwaysTrueButReturnsAny, a$, b$) // $ExpectType Observable<A | B>
-});
+});

packages/rxjs/spec-dtslint/operators/concatWith-spec.ts

@@ -1,6 +1,6 @@
 import { of } from 'rxjs';
 import { concatWith } from 'rxjs/operators';
-import { a$, b$, c$, d$, e$ } from 'helpers';
+import { a$, b$, c$, d$, e$ } from '../helpers';
 
 it('should support rest params', () => {
   const arr = [b$, c$];