Various Fixes and Improvements

• Add a checkbox into the graphical interface in order to disable or enable system notifications whenever recognizing a song (thanks to @damonhayhurst).
• Fix the bug that previously caused the Firefox user interface menus to blink on Linux after the "Search on YouTube" feature has been used (thanks to @ducaton).
• Update the French translation.
• Add safety checks in order to prevent potential crashes when handling corrupt configuration files or invalid audio devices.
• Change the path of the files saving user interface-related preferences in order to update a deprecated Rust crate (this may create a symbolic link from ~/.local/share/songrec towards an preexisting ~/.local/share/SongRec directory under Linux).