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/test/bundling/todo/index.ts

@@ -14,7 +14,8 @@ import {Component, Injectable, IterableDiffers, NgModule, defineInjector, ɵNgOn
 export class Todo {
   editing: boolean;
 
-  private _title: string;
+  // TODO(issue/24571): remove '!'.
+  private _title !: string;
   get title() { return this._title; }
   set title(value: string) { this._title = value.trim(); }