Under Bazel, some compilerOptions in tsconfig.json are controlled by
downstream rules. The default tsconfig.json causes Bazel to print out
warnings about overriden settings.
This commit makes a backup of the original tsconfig.json and removes
tsconfig settings that are controlled by Bazel.
As part of this fix, JsonAst utils are refactored into separate package
and unit tests are added.
PR closes https://github.com/angular/angular/issues/28034
PR Close#28674