Bump proto definitions to version 1

[webmaster128]

The Cosmos SDK is struggeling with protobuf version changes to the degree that it becomes clear releasing Stargate with "v1beta1" was a mistake. The plan is not to use the simple linear versioning with "v1" from 0.44 on (cosmos/cosmos-sdk#9446 (comment)).

We can avoid repeating this mistake and start the version counting now with v1.

Proposed changes in v1:

• MsgMigrateContract.migrateMsg -> .msg (analogue to MsgExecuteContract)
• MsgInstantiateContract.initMsg -> .msg (analogue to MsgExecuteContract)

[ethanfrey]

Yeah, backwards compatibility is a bit harder than it looks like. And hiding behind "beta" doesn't really help when the code is on many main nets.

Let's make a final v1 and stick with it.

[webmaster128]

v1 should be the protobuf version for 0.18. If we need a v2, v3, v4, … on the way to wasmd 1.0, then this is fine. Clients can handle it.