Convert The Great Separator into a tweak

[anna-is-cute]

This PR ports the code from The Great Separator into a tweak. If unfamiliar, that plugin adds separators to various numbers (like damage numbers). 1000 becomes 1,000 for US English, for example.

I've tested it and it works as expected. I wasn't sure how to get it to appear in the UI tab, even though I had it inherit UiAdjustments.SubTweak.

Let me know if you need anything else or if you don't want to accept this. Thank you c:

[Caraxi]

I'll accept this but will likely not be until I do updates for Dawntrail

[anna-is-cute]

No problem! Thank you!