Android: Make it possible to associate with files
Summary:
Put the file into a file descriptor and open this file descriptor.
Just application/pdf for now.
Test Plan: opened some documents on my phone
Reviewers: Okular, aacid, mart
Reviewed By: mart
Subscribers: okular-devel
Tags: Okular
Differential Revision: https://phabricator.kde.org/D12770