feat(core): deprecate integration with the Web Tracing Framework (WTF) (#30642)

DEPRECATION:

Angular previously has supported an integration with the Web Tracing
Framework (WTF) for performance testing of Angular applications. This
integration has not been maintained and likely does not work for the
majority of Angular applications today. As a result, we are deprecating
the integration in Angular version 8.

This deprecation covers the following public APIs:
* `WtfScopeFn`
* `wtfCreateScope`
* `wtfStartTimeRange`
* `wtfEndTimeRange`
* `wtfLeave`

FW-1338 #resolve

PR Close #30642

tools/public_api_guard/core/core.d.ts

@@ -1440,14 +1440,19 @@ export declare class WrappedValue {
     static wrap(value: any): WrappedValue;
 }
 
+/** @deprecated */
 export declare const wtfCreateScope: (signature: string, flags?: any) => WtfScopeFn;
 
+/** @deprecated */
 export declare const wtfEndTimeRange: (range: any) => void;
 
+/** @deprecated */
 export declare const wtfLeave: <T>(scope: any, returnValue?: T) => T;
 
+/** @deprecated */
 export interface WtfScopeFn {
     (arg0?: any, arg1?: any): any;
 }
 
+/** @deprecated */
 export declare const wtfStartTimeRange: (rangeType: string, action: string) => any;