Do not use copied autogenerated files for x/rollapp

[keruch]

Dymint imported the Hub previously, but now Cosmos versions are different as well as other deps, so direct import doesn't work currently. As a workaround, the autogenerated proto contracts were copied from the Hub to Dymint. Copying autogenerated files is not safe (it can lead to dependencies mismatch), it's impossible to find what was the original proto for these files, and it's extremely inobvious how to add new fields to such proto contracts (apparently find a suitable generator, generate files using it, and then manually copy them?).

This PR moves x/rollapp proto contracts from the Hub to Dymint, so the files are generated directly in the Dymint repo with its own proto generator.