fix(files): Reset drop notice on firefox

[susnux]

Summary

On Firefox there is an old bug where when you move a dragged file outside the window the dragleave event is never emitted. So we just use a timeout to reset the drag over state.

Also a small change: Use the ID of the main container instead of relying on tag name and class. (The ID is guaranteed as other APIs rely on it, while the class is just used internally).

Screen recording

This is how the bug looks (before this PR):

Bildschirmaufnahme_20240824_120143.webm

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[susnux]

Firefox bugs that cause this:

1. https://bugzilla.mozilla.org/show_bug.cgi?id=1427644
2. https://bugzilla.mozilla.org/show_bug.cgi?id=656164

And yes those are open since Firefox 4(!)

[susnux]

/backport to stable30

[susnux]

/backport to stable29

[susnux]

/compile

[susnux]

BTW not sure if this has side effects, but to prevent them if they exist I do not like
delete this.$route.query.XY but prefer creating a copy first so we do not trigger side effects until the $router.push.

[susnux]

/compile amend/

[skjnldsv]

/backport to stable28