use git submodules for osmosis protos

[pyramation]

Would you consider using submodule with fixing version in generate script? Something similar to this so we can keep track the dependency version https://github.com/osmosis-labs/osmosis-rust/blob/d69974b8634cbb7cd576d7139bfe7defe3a1502b/packages/proto-build/src/main.rs#L34