[nostalgia/core/studio] Cleanup and decouple main TileSheetEditor drawing from ImGui

src/nostalgia/core/studio/CMakeLists.txt

@@ -1,6 +1,5 @@
 add_library(
 	NostalgiaCore-Studio OBJECT
-		#imgconv.cpp
 		#import_tilesheet_wizard.cpp
 		module.cpp
 		#new_tilesheet_wizard.cpp
@@ -9,8 +8,6 @@ add_library(
 		tilesheeteditor.cpp
         tilesheetpixelgrid.cpp
 		tilesheetpixels.cpp
-		#util.cpp
-		#rsrc.qrc
 )
 
 if(NOT MSVC)