use ANSI escape codes to control all console text colours (#467)

More consistent and better control over console text colours.

Notably, the update reminder banner has better sized background colour
now.

Before:
![image](https://github.com/user-attachments/assets/83bf5b6c-6c66-4d95-9a10-ed4a9d2e08c1)

After:
![image](https://github.com/user-attachments/assets/49428a8f-5f18-450a-a66d-36ec778dcfb6)

https://desire2learn.atlassian.net/browse/VUL-423

src/D2L.Bmx/ConsoleWriter.cs

@@ -2,23 +2,58 @@ namespace D2L.Bmx;
 
 internal interface IConsoleWriter {
 	void WriteParameter( string description, string value, ParameterSource source );
+	void WriteUpdateMessage( string text );
+	void WriteWarning( string text );
+	void WriteError( string text );
 }
 
 // We use ANSI escape codes to control colours, because .NET's `Console.ForegroundColor` only targets stdout,
 // if stdout is redirected (e.g. typical use case for `bmx print`), we won't get any coloured text on stderr.
-// https://github.com/dotnet/runtime/issues/83146
+// See https://github.com/dotnet/runtime/issues/83146.
+// Furthermore, ANSI escape codes give us greater control over the spread of custom background colour.
+// TODO: use a library to manage ANSI codes and NO_COLOR?
 internal class ConsoleWriter : IConsoleWriter {
 	// .NET runtime subscribes to the informal standard from https://no-color.org/. We should too.
 	// https://github.com/dotnet/runtime/blob/v9.0.0-preview.6.24327.7/src/libraries/Common/src/System/Console/ConsoleUtils.cs#L32-L34
-	private static readonly bool _noColor = Environment.GetEnvironmentVariable( "NO_COLOR" ) == "1";
+	private readonly bool _noColor
+		= Environment.GetEnvironmentVariable( "NO_COLOR" ) == "1" || !VirtualTerminal.TryEnableOnStderr();
 
 	void IConsoleWriter.WriteParameter( string description, string value, ParameterSource source ) {
-		if( _noColor || !VirtualTerminal.TryEnableOnStderr() ) {
+		if( _noColor ) {
 			Console.Error.WriteLine( $"{description}: {value} (from {source})" );
 		}
 		// description: default
 		// value: bright cyan
 		// source: grey / bright black
 		Console.Error.WriteLine( $"\x1b[0m{description}: \x1b[96m{value} \x1b[90m(from {source})\x1b[0m" );
 	}
+
+	void IConsoleWriter.WriteUpdateMessage( string text ) {
+		if( _noColor ) {
+			Console.Error.WriteLine( text );
+		}
+		string[] lines = text.Split( '\n' );
+		int maxLineLength = lines.Max( l => l.Length );
+		foreach( string line in lines ) {
+			string paddedLine = line.PadRight( maxLineLength );
+			Console.Error.WriteLine( $"\x1b[0m\x1b[30;47m{paddedLine}\x1b[0m" );
+		}
+		Console.Error.WriteLine();
+	}
+
+	void IConsoleWriter.WriteWarning( string text ) {
+		if( _noColor ) {
+			Console.Error.WriteLine( text );
+		}
+		// bright yellow - 93
+		Console.Error.WriteLine( $"\x1b[0m\x1b[93m{text}\x1b[0m" );
+	}
+
+	void IConsoleWriter.WriteError( string text ) {
+		if( _noColor ) {
+			Console.Error.WriteLine( text );
+		}
+		// bright red - 91
+		Console.Error.WriteLine( $"\x1b[0m\x1b[91m{text}\x1b[0m" );
+	}
 }

src/D2L.Bmx/OktaAuthenticator.cs

@@ -91,11 +91,10 @@ mfaFactor is OktaMfaQuestionFactor // Security question factor is a static value
 			if( File.Exists( BmxPaths.CONFIG_FILE_NAME ) ) {
 				CacheOktaSession( user, org, sessionResp.Id, sessionResp.ExpiresAt );
 			} else {
-				Console.ResetColor();
-				Console.ForegroundColor = ConsoleColor.Yellow;
-				Console.Error.WriteLine( "No config file found. Your Okta session will not be cached. " +
-				"Consider running `bmx configure` if you own this machine." );
-				Console.ResetColor();
+				consoleWriter.WriteWarning(
+					"No config file found. Your Okta session will not be cached. " +
+					"Consider running `bmx configure` if you own this machine."
+				);
 			}
 			return new AuthenticatedOktaApi( Org: org, User: user, Api: oktaApi );
 		}

src/D2L.Bmx/Program.cs

@@ -246,7 +246,7 @@
 			}
 
 			if( context.ParseResult.CommandResult.Command != updateCommand ) {
-				var updateChecker = new UpdateChecker( new GitHubClient(), new VersionProvider() );
+				var updateChecker = new UpdateChecker( new GitHubClient(), new VersionProvider(), new ConsoleWriter() );
 				await updateChecker.CheckForUpdatesAsync();
 			}
 
@@ -258,17 +258,15 @@
 		order: MiddlewareOrder.ExceptionHandler + 1
 	)
 	.UseExceptionHandler( ( exception, context ) => {
-		Console.ResetColor();
-		Console.ForegroundColor = ConsoleColor.Red;
+		IConsoleWriter consoleWriter = new ConsoleWriter();
 		if( exception is BmxException ) {
-			Console.Error.WriteLine( exception.Message );
+			consoleWriter.WriteError( exception.Message );
 		} else {
-			Console.Error.WriteLine( "BMX exited with unexpected internal error" );
+			consoleWriter.WriteError( "BMX exited with unexpected internal error" );
 		}
 		if( Environment.GetEnvironmentVariable( "BMX_DEBUG" ) == "1" ) {
-			Console.Error.WriteLine( exception );
+			consoleWriter.WriteError( exception.ToString() );
 		}
-		Console.ResetColor();
 	} )
 	.Build()
 	.InvokeAsync( args );

src/D2L.Bmx/UpdateChecker.cs

@@ -5,7 +5,7 @@
 
 namespace D2L.Bmx;
 
-internal class UpdateChecker( IGitHubClient github, IVersionProvider versionProvider ) {
+internal class UpdateChecker( IGitHubClient github, IVersionProvider versionProvider, IConsoleWriter consoleWriter ) {
 	public async Task CheckForUpdatesAsync() {
 		try {
 			var updateCheckCache = GetUpdateCheckCacheOrNull();
@@ -29,7 +29,7 @@ public async Task CheckForUpdatesAsync() {
 			Version? localVersion = versionProvider.GetAssemblyVersion();
 			if( latestVersion > localVersion ) {
 				string? displayVersion = versionProvider.GetInformationalVersion() ?? localVersion.ToString();
-				DisplayUpdateMessage(
+				consoleWriter.WriteUpdateMessage(
 					$"""
 					A new BMX release is available: v{latestVersion} (current: {displayVersion})
 					Run "bmx update" now to upgrade.
@@ -41,27 +41,6 @@ public async Task CheckForUpdatesAsync() {
 		}
 	}
 
-	private static void DisplayUpdateMessage( string message ) {
-		var originalBackgroundColor = Console.BackgroundColor;
-		var originalForegroundColor = Console.ForegroundColor;
-
-		Console.BackgroundColor = ConsoleColor.Gray;
-		Console.ForegroundColor = ConsoleColor.Black;
-
-		string[] lines = message.Split( "\n" );
-		int consoleWidth = Console.WindowWidth;
-
-		foreach( string line in lines ) {
-			Console.Error.Write( line.PadRight( consoleWidth ) );
-			Console.Error.WriteLine();
-		}
-
-		Console.BackgroundColor = originalBackgroundColor;
-		Console.ForegroundColor = originalForegroundColor;
-		Console.ResetColor();
-		Console.Error.WriteLine();
-	}
-
 	private static void SetUpdateCheckCache( Version version ) {
 		var cache = new UpdateCheckCache(
 			VersionName: version,

src/D2L.Bmx/WriteHandler.cs

@@ -118,7 +118,7 @@ bool useCredentialProcess
 					}
 					parser.WriteFile( awsConfigFilePath, awsConfig, Utf8 );
 					if( foundCredentialProcess ) {
-						Console.WriteLine(
+						consoleWriter.WriteWarning(
 """
 An existing profile with the same name using the `credential_process` setting was found in the default config file.
 The setting has been removed, and static credentials will be used for the profile.