Fix rendering of reexported macros 2.0 and fix visibility of reexported items
So, this PR grew a bit out of focus, it does the following things:
* Fixes#86276.
* Fixes visibility display for reexported items: it now takes the visibility of the "use" statement rather than the visibility of the reexported item itself).
* Fixes the display of reexported items if "--document-private-items" option is used. Before, they were simply skipped.
* Fixes inconsistency on typedef items: they didn't display their visibility contrary to other items.
I added tests to check everything listed above.
cc `@camelid` `@ollie27` (in case one of you want to review?)
r? `@jyn514`