Port away from kdelibs4support

Summary:
It was only used as fallback when baloo was not found, but
`KFileMetaDataWidget` is useless without nepomuk.

The result of this patch is that the information panel and the tooltips
won't be available from platforms without baloo (instead of being
available but broken). The baloo dependency remains optional.

Closes T8720

Test Plan:
Build dolphin with `cmake -DCMAKE_DISABLE_FIND_PACKAGE_KF5Baloo=ON ..` and
make sure it doesn't show tooltips or the information panel.

Reviewers: #dolphin, broulik, ngraham

Subscribers: kfm-devel

Tags: #dolphin

Maniphest Tasks: T8720

Differential Revision: https://phabricator.kde.org/D14814