Unused imports does not detect unused import as part of a repeated alias

[dballesteros7]

Suppose you have:

import 'package:foo' as foo;
import 'package:foo_extension' as foo;

And later down the road someone removes all uses of the symbols imported from foo_extension from the library.

The analyzer will not report the foo_extension import as unused as long as foo itself is used even if it's just for the symbols in package:foo.

I'd expect that the check goes one level deeper with aliased imports and verifies that indeed something from the import is being used through the alias.