[Issue #7493] Add buttons to open locations for the various OpenMW file paths

• Issue #7493
• Summary of the changes made
  • create new tab in settingspage (files/ui/settingspage.ui)
  • move Files::applicationName from cpp to hpp (components/files/configurationmanager.xxx)
  • add actions to open folder buttons (apps/launcher/settingspage.cpp)
• Reasoning / motivation behind the change
  • #7493
  • https://forum.openmw.org/viewtopic.php?p=73979
• What testing you have carried out to verify the change.
  • Only launcher should be impacted, tested on Ubuntu 22.04

This a duplication of merge request !3275 (closed). Sorry about that, I made bad git manipulations.

Comments in original request :

From @jvoisin about void Launcher::SettingsPage::on_pathConfigurationFolderButton_clicked() in apps/launcher/settingspage.cpp.

Wouldn't one of the functions defined here work?

From @AnyOldName3

This unfortunately doesn't deal with the key problem that the launcher's idea about what the paths are can be wrong. See #6846 (closed).