Refactor, remodel, and re-do prefix mapping

[caufieldjh]

Fixes #72 and #67

Also, Poetry!

Also, emitting stats files in a predictable manner, because that's a small feature.

[caufieldjh]

• Restructure the SSSOM maps in mappings dir to follow what universalizer expects

[caufieldjh]

Got myself in a nasty merge conflict here in the process of trying to remove all the mappings (there will need to be an alternative solution to all those maps)

[caufieldjh]

All other changes will need to be made in universalizer, as there's still a collection of parsing inaccuracies.
Otherwise this works.