Setup buf generation plugins

[aaronc]

Review documentation here on how to use buf remote generation: https://docs.buf.build/bsr/remote-generation/overview. See https://docs.buf.build/bsr/remote-generation/plugin-example for an example of creating a plugin

• Create a buf remote generation plugin cosmos-proto#39
• Create buf plugin for the legacy generator protoc-gen-go-cosmos: https://github.com/cosmos/gogoproto. After Move protoc-gen-go-cosmos here gogoproto#2 is done
• Buf plugin for protoco-gen-go-cosmos-orm
• Update buf.gen.yaml to use buf plugins
• Update Makefile to use the official buf docker image

[tac0turtle]

this is blocked on removing the replace directive in the sdk.

[aaronc]

Not necessarily. We can also create a plug-in for the current code generator

[julienrbrt]

As the Cosmos SDK is an open-source project, we need public plugins for chain developers to use.
Namely, protoc-gen-pulsar (https://github.com/cosmos/cosmos-proto) and protoc-gen-gogo (https://github.com/cosmos/gogoproto).
We wanted as well to allow the usage of generated sdk thanks to the public plugin plugins, as we do for the default protocol buffer plugin.
However, due to buf change of pricing (https://buf.build/pricing) and them not having pricing for open-source project, I believe we cannot implement that anymore and neither make use of plugins and generated sdk.