Allow routes to have different grades for different disciplines

[musoke]

There are occasionally climbs that are done in more than one discipline.

• https://openbeta.io/climbs/2b6b132f-3c38-571a-b4ee-287b9e2f277b is climbed as both a tall boulder problem (V2) and a short trad route (5.10d)
• https://openbeta.io/climbs/a3624f5e-e607-5a3e-9f3e-a8d4ccc68dc0 is typically aided at 5.8 C2 but is occaisionally free climbed at 5.14
• https://openbeta.io/climbs/b8d5b6bd-a258-5dd9-ba3d-911952587df6 and https://openbeta.io/climbs/6273041a-755d-5714-8e57-92e310ac42e0 are the same route with different disciplines
• The UK uses different scales for sport and trad. Are there any routes which are done in both styles? If so, they would benefit from different grades.
• Are ice/rock routes done in winter/summer covered by this? I don't know enough.

Related

Solving this is likely required to fix
#145 Refactor climbing data to separate bouldering VScale from YDS grade system.

#233 and OpenBeta/sandbag#80 are related but slightly orthogonal - they are also about the more specific problem of mandatory-free grades for aid routes. The solution there may be most of the solution for this issue too.