inconsistency of proto msg's namespace

[hallazzang]

In the proto files, liquidity types are defined under tendermint.liquidity.v1beta1 package.

https://github.com/tendermint/liquidity/blob/e118e210d418594210f4f4862e03de1bfac6d050/proto/tendermint/liquidity/v1beta1/liquidity.proto#L2

But for the query endpoints, it uses /cosmos/liquidity/v1beta1/ as the path prefix.

https://github.com/tendermint/liquidity/blob/e118e210d418594210f4f4862e03de1bfac6d050/proto/tendermint/liquidity/v1beta1/query.proto#L16

We have to make it consistent around the files not to confuse users. But for backward compatibility we cannot change it now. We can fix this maybe in the next version of the liquidity module.