Tweaks: Allow TweaksEditorSettings to restrict the type of array items

[AndrioCelos]

Most of the time, when a mod settings file includes an array, it expects the elements of the array to be of a specific type. I propose that a field in TweaksEditorSettings be added which will allow the mod to specify the expected type of array items, so that the Mod Settings UI automatically selects that type rather than asking the user to choose a type.