Refactor kio_gdrive to make use of new GDriveUrl functionalities

Summary: D20064 enhances GDriveUrl with new constants and some of the same logic used in KIOGDrive. This patch refactors KIOGDrive to make use of it.

Reviewers: elvisangelaccio

Subscribers: KIO GDrive

Tags: KIO GDrive

Differential Revision: https://phabricator.kde.org/D20941