UI/updater: Add opt to disable building update module

Mostly to reduce build time when the update module doesn't need to be
rebuilt.

UI/win-update/updater/CMakeLists.txt

@@ -2,6 +2,10 @@ if(NOT ENABLE_WIN_UPDATER)
 	return()
 endif()
 
+if(DISABLE_UPDATE_MODULE)
+	return()
+endif()
+
 if(NOT DEFINED STATIC_ZLIB_PATH OR "${STATIC_ZLIB_PATH}" STREQUAL "")
 	message(STATUS "STATIC_ZLIB_PATH not set, windows updater disabled")
 	return()