sysusers/provides: parse and output static IDs
    
    This adds support for parsing static UIDs and GIDs from sysusers.d
    fragments, and automatically forwarding them to the generated
    'Provides' entries.
    It will allow inspecting users/groups with static IDs directly
    from package metadata:
    ```
    $ rpm --query --provides --package gdm-41.0-3.fc36.x86_64.rpm
    [...]
    group(gdm) = 42
    user(gdm) = 42
    ```