To avoid freezes, don't check if recent files exist
Inkscape checked if recent files exist, to clean up the recent files menu and the command palette. Furthermore, for the command palette the modification date of files was queried.
However, this could lead to "freezes" where Inkscape got stuck for 30 seconds or even more. These freezes occured at startup or when opening the command palette.
Therefore, all these file operations are removed.
Background:
Any stat() operation can take very long if the file path refers to an inaccessible drive (Windows: network drive with unreachable host, Linux: unplugged USB drive with automount, nonexistent host with afuse,...).
Fixes https://gitlab.com/inkscape/inkscape/-/issues/2348