Add divisions to matches

[slmnio]

We've long used sub events to distinguish separate divisions on a match, but it isn't really the intended use case, and can cause issues on some overlays such as match history. A separate field would help to keep the uses consistent across graphics.

• [ ] Add division field to matches
• [ ] Add to formats (Twitch title, ingame details, middle #262)
• [ ] Update head-to-head map details to work with divisions (if necessary? at least displaying it)
• [ ] Add to the match string that's generated under thumbnails