build(bazel): Turning on strictPropertyInitialization for Angular. (#24572)

All errors for existing fields have been detected and suppressed with a
`!` assertion.

Issue/24571 is tracking proper clean up of those instances.

One-line change required in ivy/compilation.ts, because it appears that
the new syntax causes tsickle emitted node to no longer track their
original sourceFiles.

PR Close #24572

packages/core/testing/src/async_test_completer.ts

@@ -10,8 +10,10 @@
  * Injectable completer that allows signaling completion of an asynchronous test. Used internally.
  */
 export class AsyncTestCompleter {
-  private _resolve: (result: any) => void;
-  private _reject: (err: any) => void;
+  // TODO(issue/24571): remove '!'.
+  private _resolve !: (result: any) => void;
+  // TODO(issue/24571): remove '!'.
+  private _reject !: (err: any) => void;
   private _promise: Promise<any> = new Promise((res, rej) => {
     this._resolve = res;
     this._reject = rej;