Incorporate LUS CMake CVar system (#4093)

* Incorporate LUS CMake CVar system.
Customize all LUS CMake CVars to align with plans for preset system.
Swap "gOverlayFont" usage back to LUS CVar macro.

* Change CMake sets to use the cache to allow for including LUS's file for the add_compile_defines and remove the duplication on SoH's side.

* Move SoH CMake CVars to `soh-cvars.cmake` for clarity.

soh/src/code/game.c

@@ -467,7 +467,7 @@ void GameState_Destroy(GameState* gameState) {
     // Performing clear skeletons before unload resources fixes an actor heap corruption crash due to the skeleton patching system.
     ResourceMgr_ClearSkeletons();
 
-    if (CVarGetInteger("gAltAssets", 0)) {
+    if (CVarGetInteger(CVAR_ALT_ASSETS, 0)) {
         ResourceUnloadDirectory("alt/*");
         gfx_texture_cache_clear();
     }