feat(files): add drag and drop support

[skjnldsv]

Informations

This PR adds drag and dro psupport for files

• You can drag a file to a folder
• You can start a selection and drag that selection to a folder
• You can press ctrl or caps to switch beteen moving or copying when dragging
• There is no conflict picker, this does not exists on older versions
  see Copy file fails if filename already exists in the target folder #30388

Bug

• The loading indicator seems broken, this is a vue reactivity issue that will be fixed later, this is not related to this PR :)

Ref #39914

Fix #18850
Fix #37658
Fix #5356

• Move mechanism (bind to the move action?)
• Visual feedback

[skjnldsv]

@nextcloud/designers I'm close to finish this and a question popped up. When selecting a big set of files and folder, maybe it would be safe to have an alert and ask confirmation before drag-dropping to another folder? Because we currently have no cancellation button, so if you misclick and drop to another folder, might have bad outcomes? 🤔

[marcoambrosini]

When selecting a big set of files and folder, maybe it would be safe to have an alert and ask confirmation before drag-dropping to another folder?

@skjnldsv Without a toggle for this in the settings, I'm afraid this could get in the way of people who are sure about what they're doing

[skjnldsv]

@skjnldsv Without a toggle for this in the settings, I'm afraid this could get in the way of people who are sure about what they're doing

When dragging 100+ files, any confirmation is better than a potential destructive outcome, no? cc @jancborchardt