fix(files): Properly handle denied ownership transfers

fix(files): Properly handle denied ownership transfers

When the receiver denies the transfer the notification handler was missing,
so no notification was created for the transfer owner.

But also the internal notification was created two times:
1. When rejecting the transfer
2. By the reject function when dismissing the notification

This is fixed by only relying on the dismiss function.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>