feat(language-service): Show documentation on hover (#34506)

This commit adds dpcumentation to the hover tooltip.

PR closes https://github.com/angular/vscode-ng-language-service/issues/321

PR Close #34506

packages/language-service/src/global_symbols.ts

@@ -43,6 +43,10 @@ export const createGlobalSymbolTable: (query: ng.SymbolQuery) => ng.SymbolTable
           callable: true,
           definition: undefined,
           nullable: false,
+          documentation: [{
+            kind: 'text',
+            text: 'function to cast an expression to the `any` type',
+          }],
           members: () => EMPTY_SYMBOL_TABLE,
           signatures: () => [],
           selectSignature(args: ng.Symbol[]) {