Follow proto dir best practice (in cosmos eco)

[alpe]

I found more and more projects that store the protobuf files into

• proto/ - for their own files
• third_party/proto - for the dependencies

This will make it easier to maintain multiple versions in the future but also works more nicely with buf linter.
On the downside these folders are not resolved by the Golang IDE automatically for dependencies.

[ethanfrey]

I like this idea. I've never had much IDE support for proto files, so I won't miss it (as long as the generated *.pb.go files work with the IDE).

[willclarktech]

This would also align us with Cosmos SDK.