Comparison of `MAPINFO`-related formats -- potential additions to `UMAPINFO`

What features are present across each and every format of this type? Which features would be useful, and in scope, to be possibly added to the cross-port `UMAPINFO`?

Lumps to consider:
* `MAPINFO` Hexen, ZDoom
* `DMAPINFO` Doom Classic Unity
* `DD_DEFNS` Doomsday, Risen3D
* `EMAPINFO` Eternity Engine
* `RMAPINFO` Doom Retro
* `ZMAPINFO` ZDoom

CC @thecnoNSMB , @andrikpowell