This PR adds the support for pinning files.
Users can right click on a tab/file(working file) and from the context menu select the 'Pin' option:

the pinned files will be displayed at the first before the regular files,
they are protected from bulk close operations like (Close all, close others, etc)
close button is replaced with a pin button and users need to unpin to close the tab/file.

Feature idea from : #2024