build(compiler-cli): enable full TypeScript strictness (#29436)

This commit enables strict: true in TypeScript builds of
//packages/compiler-cli.

PR Close #29436

packages/compiler-cli/src/ngtsc/shims/src/host.ts

@@ -81,7 +81,7 @@ export class GeneratedShimsHostWrapper implements ts.CompilerHost {
   writeFile(
       fileName: string, data: string, writeByteOrderMark: boolean,
       onError: ((message: string) => void)|undefined,
-      sourceFiles: ReadonlyArray<ts.SourceFile>): void {
+      sourceFiles: ReadonlyArray<ts.SourceFile>|undefined): void {
     return this.delegate.writeFile(fileName, data, writeByteOrderMark, onError, sourceFiles);
   }