Clean-ups and bug fixes release

• Fixed long standing issue with Mouse cursor brightness control not working on Gnome 40 and later.
• Declare compatibility with version 40 and 41 of Gnome Shell instead of using minor versions (40.0 and 41.1). This should clear reports of the extension being incompatible with well-supported versions.
• Drop compatibility with Gnome Shell 3.28 and 3.30 (which do not have getSettings/initTranslations in ExtensionUtils).
• Update meson-gse:
  • Fix build issues with meson 0.60.0.
  • Bump minimum meson version to 0.50.0.
• Clean up code:
  • Remove Lang imports.
  • Use ExtensionUtils for getSettings/initTranslations instead of using meson-gse's convenience.js.
  • Drop old Gnome Shell 3.28 compatibility code.