The current "go to definition" is broken for template variables and
references when a template is overridden. This is because we get the
file url from the source span, which uses the overridden name
'override.html'. Instead, we can retrieve the template file from the
compiler in the same manner that is done for references.
Another way to fix this would have been to use the real template file path when
overriding a template, but this was the more straightforward fix since
the strategy was already used in find references and rename locations.
fixes https://github.com/angular/vscode-ng-language-service/issues/1054
PR Close#40455