This commit elaborates diagnostics produced for invalid template
contexts by including the name of the embedded template type using the
template context, and in the common case that the implicity property is
being referenced (e.g. in a `for .. of ..` expression), suggesting to
refine the type of the context. This suggestion is provided because
users will sometimes use a base class as the type of the context in the
embedded view, and a more specific context later on (e.g. in an
`ngOnChanges` method).
Closes https://github.com/angular/vscode-ng-language-service/issues/251
PR Close#34751
4ba478267e