AchievementApprovedHash: Automatically generate hash using CMake

CMake/GenerateAchievementHash.cmake

@@ -0,0 +1,5 @@
+# This file exists to be consumed via `add_custom_command`
+# so that file changes are picked up without needing a full reconfigure
+
+file(SHA1 ${JSON_FILE} ACHIEVEMENT_APPROVED_LIST_HASH)
+configure_file(${TEMPLATE_FILE} ${OUTPUT_FILE} @ONLY)