prefs: use common defines for all simple pref tab titles & tooltips

(Split from !307)

only two such defines were already in use, the rest were pointlessly duplicating the text, which should be identical in both interfaces and so it makes sense to have shared defines.

this happens to fix a few unwanted inconsistencies:

• macos was using lowercase "settings" in two places.
• qt was using completely different language for the hotkey and ml tag tooltips to everything else.
• a trivial difference between input tab tooltips.