Enable opening on connected device (Android)

Summary: When a Share packet with a file and "open: true" arrives ope that file directly. Files are always downloaded to the standard location to avoid the FileProvider trouble

Test Plan: TBA

Reviewers: KDE Connect, albertvaka

Reviewed By: KDE Connect, albertvaka

Subscribers: albertvaka, kdeconnect

Tags: KDE Connect

Maniphest Tasks: T8637

Differential Revision: https://phabricator.kde.org/D15293