Add UDev find module

Summary:
This one is originally coming from Solid, but there are several more copies
in our repositories (plasma-desktop, kwin, powerdevil, etc).

Reviewers: cgiboudeaux

Reviewed By: cgiboudeaux

Subscribers: cgiboudeaux, kde-frameworks-devel, kde-buildsystem

Tags: Frameworks, Build System

Differential Revision: https://phabricator.kde.org/D19486