handle "custom" stats used by certain moves and assets

[rsek]

off the top of my head, there's two:

dataforged defines these in trigger options. both labels and values are defined to make it fairly simple to render them as a dropdown or similar input:

however: it might also make sense "advanced" roll setting to just use an arbitrary integer value as the stat. it'd have the fringe benefit of offering a workaround for ppl needing a custom value or just one that isn't handled by the module yet.