Modding: Validate unique parameters for mods

Display protecting civs for city-states

Movement fix: units check if they can capture enemy units by whether they *will* be embarked, not by whether they *are* embarked

By letstalkaboutdune:
- SFX Update - Arrow, Crossbow (New), Metal Hit

Fixed crash when policy prerequisite is a branch  - By vegeta1k95

Fix another untranslated String in Policy Screen  - By CrispyXYZ

added buttons for controlling music  - By alexban011