Define QueryResponse and QueryRequest protobufs.

[jeschkies]

What this PR does / why we need it:
This will be a follow up to #10688 finally switching over to protos. Hang on tight!

TODO

• Introduce metadata and forward query tags and actor paths in protobuf.
• Enable GEL to use metadata to pass LBAC policies.
• Propagate trace context in gRPC too - this will be ignored if using HTTP.

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• CHANGELOG.md updated
  • If the change is worth mentioning in the release notes, add add-to-release-notes label
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• For Helm chart changes bump the Helm chart version in production/helm/loki/Chart.yaml and update production/helm/loki/CHANGELOG.md and production/helm/loki/README.md. Example PR

[jeschkies]

func HttpgrpcToHTTPResponse(resp *httpgrpc.HTTPResponse) *http.Response {
	httpResp := &http.Response{
		StatusCode:    int(resp.Code),
		Body:          &buffer{buff: resp.Body, ReadCloser: io.NopCloser(bytes.NewReader(resp.Body))},
		Header:        http.Header{},
		ContentLength: int64(len(resp.Body)),
	}
	for _, h := range resp.Headers {
		httpResp.Header[h.Key] = h.Values
	}

	return httpResp
}

func HTTPtoHttpgrpcResponse(resp *http.Response) (*httpgrpc.HTTPResponse, error) {
	var buf []byte
	var err error
	if buffer, ok := resp.Body.(Buffer); ok {
		buf = buffer.Bytes()
	} else {
		buf, err = io.ReadAll(resp.Body)
		if err != nil {
			return nil, httpgrpc.Errorf(http.StatusInternalServerError, "error decoding response: %v", err)
		}
	}

	grpcResp := &httpgrpc.HTTPResponse{
		Code: int32(resp.StatusCode),
		Body: buf,
	}
	for k, v := range resp.Header {
		grpcResp.Headers = append(grpcResp.Headers, &httpgrpc.Header{Key: k, Values: v})
	}

	return grpcResp, nil
}

[cstyan]

Are the todos in the opening of the PR still relevant?

[jeschkies]

Are the todos in the opening of the PR still relevant?

@cstyan they are all done.

[dannykopping]

LGTM! Minor non-blocking comments
Let's land it 🚀

[dannykopping]

Was this implemented? I don't see it
It can also be a note in the upgrade guide if it's a pain

[dannykopping]

Non-blocking:
Was surprised by this; shouldn't we automatically inject the orgID into the request when encoding it?

[jeschkies]

Awesome catch!