GRPCRoute Hostnames and BackendRef

[mpstefan]

As a user of NGF with applications that require GRPC traffic
I want NGF to support a GRPCRoute with hostname and backendref matching support
So that I have a method to ingress GRPC traffic to my applications.

Acceptance

• Users can create a GRPCRoute that can direct traffic from a hostname to a valid backendref.
• The conformance test for GRPCRoute is enabled.

Dev Notes

• A refactor is required to genericize the use of routes in the code base so that http route is not hard coded.
• The implementation should first have a draft PR for refactor above.

[ciarams87]

Draft PR: https://github.com/nginxinc/nginx-gateway-fabric/pull/1820/files