When listing refs installed or from a remote, only the refs matching the
main collection-id were being returned. However, it is very important to
have access to all refs, independently from their collection-id,
especially when trying to list remotes coming from a USB repository.
These changes add the mentioned refs and update the places that use
this list, both in the lib and in the CLI.
For the implementation to become easier, we introduce also a
FlatpakCollectionRef, that should be replaced by OstreeCollectionRef
once the latter becomes part of the general API (currently it is in the
experimental one).
Closes: #1587
Approved by: mwleeds
516e249e50