$(location) should be able to accept the label of an alias()

### Description of the bug:

This is about macros generating attributes with `location` function where an alias is used.

There is no way in Skylark to get the real label of an AliasConfiguredTarget.

Here's the horrible workaround I used:

```
labels = [target.label]
if repr(target).startswith("

Start with the Skylark macro behavior described here and trace how location(), alias(), AliasConfiguredTarget, and target.label interact; the issue names no files or tests. Done means location() can accept an alias's real label without relying on repr(target) parsing.

Written by the indexing model from the issue text.