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/symbols.ts

@@ -7,6 +7,8 @@
  */
 
 import {StaticSymbol} from '@angular/compiler';
+import * as ts from 'typescript';
+
 
 /**
  * The range of a span of text in a source file.
@@ -95,6 +97,11 @@ export interface Symbol {
    */
   readonly nullable: boolean;
 
+  /**
+   * Documentation comment on the Symbol, if any.
+   */
+  readonly documentation: ts.SymbolDisplayPart[];
+
   /**
    * A table of the members of the symbol; that is, the members that can appear
    * after a `.` in an Angular expression.