OTRGlobals cleanup (#4251)

* Remove unused headers

* Move all "ResourceMgr_" functions to a new file

* Don't transitively include SaveManager

* Move cvar prefixes to a new header

* Add missing includes

* Update OTRGlobals.cpp

* Fix build

* Address review

* Fix some of the errors

* Update gameplaystats.h

* Update z_en_in.c

* Hopefully fix the linux issues

* Fix Linux issues for real this time, I checked

* Update ResourceManagerHelpers.cpp

* Update z_obj_mure2.c

* Post-merge fixes

* Fix build (hopefully)

* Post-merge fixes

* Update z_file_nameset_PAL.c

* cleanup some unnecessary headers (#7)

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Co-authored-by: Archez <Archez@users.noreply.github.com>

soh/src/code/z_cheap_proc.c

@@ -1,4 +1,5 @@
 #include "global.h"
+#include "soh/ResourceManagerHelpers.h"
 
 void Gfx_DrawDListOpa(PlayState* play, Gfx* dlist) {
     OPEN_DISPS(play->state.gfxCtx);