[XAttrIndexer] Update DocumentTime when XAttrs are updated

Summary:
After modifying a files attributes (like ownership, permissions, tags,
...) the timestamp in the DB would be different to the filesystem
timestamp. The change would only be picked up on next login by the
UnindexedFileIndexer.

Also update the FileNameTerms and DocumentUrl, as renames also change
the ctime. As the WriteTransaction checks for changes, setting the
flags in excess is cheap, but avoids getting the filename out of sync.

Depends on D21694

Reviewers: Baloo, ngraham, astippich, poboiko

Reviewed By: astippich

Subscribers: kde-frameworks-devel

Tags: Frameworks, Baloo

Differential Revision: https://phabricator.kde.org/D21707