feat(language-service): add definitions for styleUrls (#32464)

Adds support for `styleUrls` definitions in the same way `templateUrl`
definitions are provided; clicking on styleUrl will take a user to the
respective file.

Unifies some code in determining a URL definition. We first check if a
url is a `templateUrl`; if it's not, we check that it's a `styleUrl` or
return no definitions.

PR Close #32464

integration/language_service_plugin/project/app/widget.component.ts

@@ -3,5 +3,6 @@ import { Component } from '@angular/core';
 @Component({
   selector: 'my-widget',
   templateUrl: './widget.component.html',
+  styleUrls: ['./style.css'],
 })
 export class WidgetComponent  { name = 'Angular'; }