Add button to open current openmw.cfg(s) in the launcher

Brought up here: https://forum.openmw.org/viewtopic.php?p=73979#p73979

It would save some hassle if the launcher had buttons to open the current config directory/directories. Otherwise, users have to know https://openmw.readthedocs.io/en/latest/reference/modding/paths.html exists, and then it's not even correct for the flatpak.

It would also be nice to add a butter to open the logs as well.