Ignore file extensions from other torrent clients when checking for existing data

[as-muncher]

Is your feature request related to a problem? Please describe.
I wanted to transfer my torrent data from qbittorrent, so what I did is cut and paste from the qbittorrent save directory to the tribler save directory. I add my torrent, and then do a force recheck. However, I didn't realise that I had to delete the .!qB extension first in order for tribler to recognise the data that is there. So it showed that I had less data downloaded than I really had.

Describe the solution you'd like
I'd like tribler to be able to ignore the extensions, whether .!qB or the biglybt/azureus one, or the transmission one, or the bittorrent/utorrent one.

Describe alternatives you've considered
There are renaming programs, an extra step to make the data ok for tribler.

Additional context
I'm using tribler 7.11.0
I always use an extension like .!qB or whatever for incomplete data. I hate when I think I'm downloading a file and it looks complete because it doesn't have .!qB etc on the end, and then I see that the data is incomplete, avi needs to be repaired, all that. It's frustrating. So that's why I always have that turned on, so I know what's truly complete.

[xoriole]

@as-muncher Thank you for the feature request