foldermodel.cpp: add context to menu connection
Menu connection was missing "this" as context, so it would be called even if "this" was not there anymore.
The bug I've linked before is very difficult to reproduce, it seems to be a race condition that triggers rarely for some, more often for others. I have only gotten it happen once, but the backtrace indicates this seems to be the problem.
(cherry picked from commit 2772401d)
8e83c02d foldermodel.cpp: add context to menu connection
Co-authored-by: Akseli Lahtinen akselmo@akselmo.dev