New: Ability to use Original Title only in naming settings

@Taloth @kayone This will let people keep renaming on, but selectively choose which files actually get renamed and which ones use the scene name.
I don't really like this, but currently if the Original Title is not set, we return an empty string, which feels completely broken to me, instead this will return the existing file name. There is some opportunity to make this a bit more DRY as this is almost the same block of code that is used when renaming is disabled. Could also take it further and only set the Original Title to the filename when its the only token, but have that logic when we're creating the token, instead of a separate branch, which I think I like better.