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/compiler-cli/src/metadata/symbols.ts

@@ -11,7 +11,8 @@ import * as ts from 'typescript';
 import {MetadataSymbolicReferenceExpression, MetadataValue} from './schema';
 
 export class Symbols {
-  private _symbols: Map<string, MetadataValue>;
+  // TODO(issue/24571): remove '!'.
+  private _symbols !: Map<string, MetadataValue>;
   private references = new Map<string, MetadataSymbolicReferenceExpression>();
 
   constructor(private sourceFile: ts.SourceFile) {}