Android: include metadata for okular kirigami

Summary:
Include an AndroidManifest.xml file so when it's installed it has a
proper icon and name.
Include appdata information so it can be listed

Reviewers: #okular, mart, aacid

Reviewed By: #okular, mart, aacid

Tags: #okular

Differential Revision: https://phabricator.kde.org/D12299