Make the process of packing files more straightforward and user friendly

[ags]

Using version 15.6.3119.
There are a few problems when the user interrupts the packing of files.

What MC does is send the users into a confusing labyrinth:
- asks the users if they want to abort the copy operation. Why copy, since the menu clearly says "Pack files..."
- asks the users if they want to keep or delete the current incomplete file. NB, this does not refer to the archive file, but the current file the process got to when creating the archive. Why would I want to keep a file in this step of the process?
- then another windows opens, announcing that it "Failed to remove the incomplete file". But this window appears underneath others, so it cannot be seen, so the whole process hangs until the user manages to catch on on what is happening
- however, the timer does not care about all these minor interruptions. It marches on into infinity
- the resulting archive is left incomplete on the disk
- last, but not least, when using a dark theme the process is like a chess board: some windows are dark, the next are light, then dark again... you get the point.

What is expected:
- MC asks one time for confirmation
- the process is dropped
- partially created archive is deleted

I made a video illustrating what I described above.

[Mathias (Author)]

well MC is build around virtual filesystem,  Zip is a virtual file system for example
So the concept of packing a file does not exists in MC it is really just a copy to a file inside the Zip Virtual Filesystem.
You can turn off if you do not want to to try to keep incomplete files. it really depends on the target virtual filesystem if they are supported.  most archives does not support removing a file inside a archive just like that. (often require rewriting entire archive)
They are often use when copy from archive to normal (Unpack) and there are error in the archive. so that you can keep the incomplete file anyway. since sometimes a broken file is better then none.

Dark mode. yes not all dialog windows are fixed.. Since windows does not support darkmode for old style UI . All dialog need to be modified in code by hand..  and some UI controller does not support colors being changed. so they the style of them cant be overriden, so then the design of the entire dialog need to be redone.
The most common are modified in MC.. But changing all require lots of work. and why spend a lot of hours or days to fix one dialog when that dialog are very very rarly shown.  there are a over 100+ dialogs in MC. and to fully transform them to support darkmode would require A LOT of work. I would need to spend a year just doing that. and that are boring