Add KFileItemActionPlugin for copying Google URL to clipboard.

Summary: When right clicking on a Google Drive file or folder, show a 'Copy Google URL to clipboard' context menu action.

Reviewers: elvisangelaccio

Reviewed By: elvisangelaccio

Subscribers: KIO GDrive

Tags: KIO GDrive

Differential Revision: https://phabricator.kde.org/D23874