Use client ID as fallback for diagnostics collection (#1445)

* Use client ID as fallback for diagnostics collection

This sets the language client ID as a fallback for the diagnostics
collection name. If no collection name is provided, VSCode generates
one. This name is visible in the diagnostics table view of the problems
panel.

* Use nullish coalescing to fallback to the id

This means the name can be set to an empty string.

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Co-authored-by: Dirk Bäumer <dirkb@microsoft.com>

client/src/common/client.ts

@@ -1073,9 +1073,7 @@ export abstract class BaseLanguageClient implements FeatureClient<Middleware, La
 
 		// If we restart then the diagnostics collection is reused.
 		if (this._diagnostics === undefined) {
-			this._diagnostics = this._clientOptions.diagnosticCollectionName
-				? Languages.createDiagnosticCollection(this._clientOptions.diagnosticCollectionName)
-				: Languages.createDiagnosticCollection();
+			this._diagnostics = Languages.createDiagnosticCollection(this._clientOptions.diagnosticCollectionName ?? this._id);
 		}
 
 		// When we start make all buffer handlers pending so that they