The support for decorators that were imported via a namespace,
e.g. `import * as core from `@angular/core` was implemented
piecemeal. This meant that it was easy to miss situations where
a decorator identifier needed to be handled as a namepsaced
import rather than a direct import.
One such issue was that UMD processing of decorators was not
correct: the namespace was being omitted from references to
decorators.
Now the types have been modified to make it clear that a
`Decorator.identifier` could hold a namespaced identifier,
and the corresponding code that uses these types has been
fixed.
Fixes#31394
PR Close#31426
dd664f694c