Make it possible to handle the _file_ after selecting the image (copy, move, tag, ...)

[grinapo]

Is your feature request related to a problem? Please describe.
I browse the images. I find one or some I like. I want to copy images into an already existing folder, shared, public or else.

Describe the solution you'd like
Well, both #83 and #84 would offer an approach, but since Nextcloud is actually a file storage it seems logical to be able to copy or move a selected file.

Possible solutions:

• another tab next to Chat and Sharing, which would offer file management functions, like copy, move, tag, or even helpers like copy/move into an album
• after implementing multiselect -- the same functions in whatever UI you pick to have then.
• suboptimal, but still better than nothing: a button to jump to the file in the storage. (I'm not sure it's even possible easily.)

[skjnldsv]

Duplicate of nextcloud/viewer#7 I guess :)