Update translation infrastructure
    
    1. Build po/ipa.pot every time we update PO files (each build)
    
    2. Drop any rebuilt PO changes if the only difference is in the
       translation file's header in a timestamp or timestamp+bug report
       link.
    
    3. Only apply the logic for dropping the changes if we are operating on
       a git tree checkout because there is no otherwise an easy way to
       detect the changes.
    
    4. Hook strip-po target to the cleanup target to allow dropping unneeded
       translation changes automatically.
    
    5. Finally, strip ipaclient/remote_plugins/* locations from the ipa.pot
       template. This saves us around 23,000 lines from the ipa.pot file and
       reduces visual clutter in the translation files.
    
    This approach allows to avoid unneccesary commits because even when
    there are no changes to translation files, po/ipa.pot header would be
    updated with a new translation update timestamp.
    
    Fixes: https://pagure.io/freeipa/issue/8159
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Christian Heimes <cheimes@redhat.com>