BuiltData is saved alongside it's map, even if lighting hasn't changed

Saving a map will always resave the map's BuiltData, even if the BuiltData hasn't been marked dirty. Changes were made to avoid marking it dirty for [Link Removed], but the call to SaveWorld in FEditorFileUtils::SaveLevel ignores the dirty flag and tries to save it anyway.

In 4.27, marking the map as Writeable and saving it resulted in a prompt to check out the BuiltData file. In 5.0, the second prompt did not appear and the save failed because the BuiltData was not writeable.

1. Open QA game and navigate to a map
2. Make a change to the map that does not modify lighting, such as moving a player start
3. Note that the map is marked dirty but the BuiltData is not, as expected (see [Link Removed])
4. Check out the map or mark it as writeable and save it, not that the BuiltData is also resaved