Replace v1beta1 gov with v1 where possible (47)

[alpe]

• Deprecate v1beta1 proposal content types
• use v1 in messages, simulations, tests

Note there may be inflight v1beta1 gov proposals that should still be executable but no new v1beta1 proposals allowed

[faddat]

• remove the exclusion of simtypes in .golangci.yml (this would come after addressing the gov changes)