Introduce Buf for Proto Generation

[YusukeShimizu]

Our current https://github.com/ElementsProject/peerswap/tree/9dc5c5175d59eabd611c993b09c97fd151f1acf1/peerswaprpc relies on protoc for generating code from .proto files. While protoc has served its purpose,it has several challenges:

1. Dependency Management: Maintaining imports and managing shared proto files is becoming cumbersome.
2. Tooling Limitations: Limited support for modern workflows, such as linting, breaking change detection, and streamlined plugin usage.

I would like to properly perform validation on proto, and for that, I believe protovalidate is appropriate. First, it is necessary to migrate to Buf.
Buf offers a more robust and developer-friendly solution for managing proto files and generating code.

[shelter2759]

@YusukeShimizu
Is this issue still valid? Would it be alright if I worked on it?

[YusukeShimizu]

Thank you!
Yes, this issue is still valid.