fix: public api surface fixes + stability markers

- ts-api-guardian will now error if a new public symbol is added with a stability marker (`@stable`, `@experimental`, `@deprecated`)
- DomEventsPlugin and KeyEventsPlugin were removed from public api surface - these classes is an implementation detail
- deprecated BROWSER_PROVIDERS was removed completely
- `@angular/compiler` was removed from the ts-api-guardian check since this package shouldn't contain anything that users need to directly import
- the rest of the api surface was conservatively marked as stable or experimental

BREAKING CHANGES: DomEventsPlugin and KeyEventsPlugin previously exported from core are no longer public - these classes are implementation detail.

Previously deprecated BROWSER_PROVIDERS was completely removed from platform-browser.

Closes #9236
Closes #9235
Ref #9234

tools/public_api_guard/router/index.d.ts

@@ -1,3 +1,4 @@
+/** @experimental */
 export declare class ActivatedRoute {
     component: Type | string;
     data: Observable<Data>;
@@ -8,6 +9,7 @@ export declare class ActivatedRoute {
     toString(): string;
 }
 
+/** @experimental */
 export declare class ActivatedRouteSnapshot {
     component: Type | string;
     data: Data;
@@ -17,29 +19,36 @@ export declare class ActivatedRouteSnapshot {
     toString(): string;
 }
 
+/** @experimental */
 export interface CanActivate {
     canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<boolean> | boolean;
 }
 
+/** @experimental */
 export interface CanDeactivate<T> {
     canDeactivate(component: T, route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<boolean> | boolean;
 }
 
+/** @experimental */
 export declare type Data = {
     [name: string]: any;
 };
 
+/** @experimental */
 export declare class DefaultUrlSerializer implements UrlSerializer {
     parse(url: string): UrlTree;
     serialize(tree: UrlTree): string;
 }
 
+/** @experimental */
 export declare type Event = NavigationStart | NavigationEnd | NavigationCancel | NavigationError;
 
+/** @experimental */
 export interface ExtraOptions {
     enableTracing?: boolean;
 }
 
+/** @experimental */
 export declare class NavigationCancel {
     id: number;
     url: string;
@@ -47,6 +56,7 @@ export declare class NavigationCancel {
     toString(): string;
 }
 
+/** @experimental */
 export declare class NavigationEnd {
     id: number;
     url: string;
@@ -55,6 +65,7 @@ export declare class NavigationEnd {
     toString(): string;
 }
 
+/** @experimental */
 export declare class NavigationError {
     error: any;
     id: number;
@@ -63,6 +74,7 @@ export declare class NavigationError {
     toString(): string;
 }
 
+/** @experimental */
 export declare class NavigationStart {
     id: number;
     url: string;
@@ -70,27 +82,34 @@ export declare class NavigationStart {
     toString(): string;
 }
 
+/** @experimental */
 export declare type Params = {
     [key: string]: any;
 };
 
+/** @experimental */
 export declare const PRIMARY_OUTLET: string;
 
+/** @experimental */
 export declare function provideRouter(config: RouterConfig, opts?: ExtraOptions): any[];
 
+/** @experimental */
 export interface Resolve<T> {
     resolve(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<any> | any;
 }
 
+/** @experimental */
 export declare type ResolveData = {
     [name: string]: any;
 };
 
+/** @experimental */
 export interface Route {
     path?: string;
     pathMatch?:
     /** @deprecated */ terminal?: boolean;
 
+/** @experimental */
 export declare class Router {
     events: Observable<Event>;
     routerState: RouterState;
@@ -103,14 +122,18 @@ export declare class Router {
     serializeUrl(url: UrlTree): string;
 }
 
+/** @experimental */
 export declare const ROUTER_DIRECTIVES: (typeof RouterOutlet | typeof RouterLink | typeof RouterLinkActive)[];
 
+/** @experimental */
 export declare type RouterConfig = Route[];
 
+/** @experimental */
 export declare class RouterOutletMap {
     registerOutlet(name: string, outlet: RouterOutlet): void;
 }
 
+/** @experimental */
 export declare class RouterState extends Tree<ActivatedRoute> {
     fragment: Observable<string>;
     queryParams: Observable<Params>;
@@ -118,6 +141,7 @@ export declare class RouterState extends Tree<ActivatedRoute> {
     toString(): string;
 }
 
+/** @experimental */
 export declare class RouterStateSnapshot extends Tree<ActivatedRouteSnapshot> {
     fragment: string;
     queryParams: Params;
@@ -125,6 +149,7 @@ export declare class RouterStateSnapshot extends Tree<ActivatedRouteSnapshot> {
     toString(): string;
 }
 
+/** @experimental */
 export declare class RoutesRecognized {
     id: number;
     state: RouterStateSnapshot;
@@ -134,6 +159,7 @@ export declare class RoutesRecognized {
     toString(): string;
 }
 
+/** @experimental */
 export declare class UrlPathWithParams {
     parameters: {
         [key: string]: string;
@@ -145,11 +171,13 @@ export declare class UrlPathWithParams {
     toString(): string;
 }
 
+/** @experimental */
 export declare abstract class UrlSerializer {
     abstract parse(url: string): UrlTree;
     abstract serialize(tree: UrlTree): string;
 }
 
+/** @experimental */
 export declare class UrlTree {
     fragment: string;
     queryParams: {