`RouterTestingModule` is not needed as of v16. Instead, TestBed
automatically provides `MockPlatformLocation` in order to help test
navigations in the application. The location mocks in the
RouterTestingModule aren't necessary anymore.
There doesn't appear to be any real documentation around
`RouterTestingModule` other than the API docs.
PR Close#49427
This commit adds an integration test that uses `@angular/elements` with
`@angular/platform-server` in order to highlight a current
incompatibility. The issue will be fixed in a subsequent commit.
PR Close#40559
