update to latest LUS main (#4202)

Includes supporting changes from:
* https://github.com/HarbourMasters/Shipwright/pull/4197 (alt assets variable changes)
* https://github.com/HarbourMasters/Shipwright/pull/4199 (WindowBackend enum changes)
* https://github.com/HarbourMasters/Shipwright/pull/4200 (Extract gMtxClear)

---------

Co-authored-by: Malkierian <malkierian@gmail.com>
Co-authored-by: inspectredc <inspectredc@gmail.com>

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(CVAR_ALT_ASSETS, 0)) {
+    if (ResourceMgr_IsAltAssetsEnabled()) {
         ResourceUnloadDirectory("alt/*");
         gfx_texture_cache_clear();
     }