Use Protobuf linter in CI pipeline

[ClemensLinnhoff]

Describe the feature

To ensure a certain quality of the proto files in this repo, a linter could be employed in the pipeline.

Describe the solution you would like

I found two possible actions to use:

• https://github.com/bufbuild/buf-lint-action
• https://github.com/yoheimuta/action-protolint

We could also include a spell check for the proto files as mentioned in #773 or tackle this in a separate issue.

Describe alternatives you have considered

The only alternative is what is done now: Manual checks by the CCB.