Add scale BrazilianExposure #162
Description
see discussion on PR for BrazilianCrux:
- https://github.com/OpenBeta/sandbag/pull/158/files#r1388446690
- https://github.com/OpenBeta/sandbag/pull/158/files#r1388568954
- https://www.cap.com.br/post/sistema-brasileiro-de-gradua%C3%A7%C3%A3o-de-vias-de-escalada
This is a new type of scale, so will require some work to identify other possible exposure scales and the relations between them.