Implement logging.Logger interface from go-grpc-middleware/v2

[marcoshuck]

Is your feature request related to a problem? Please describe.

The go-grpc-middleware version 2 has introduced a new way of handling logging interceptors, making the original grpczap package found in this repository impratical.

Describe the solution you'd like
This suggestion requires implementing the logging.Logger interface from the go-grpc-middleware/v2 package, as described in this example: https://github.com/grpc-ecosystem/go-grpc-middleware/blob/main/interceptors/logging/examples/zap/example_test.go#L17

Describe alternatives you've considered
I've raised this same problem in the go-grpc-middleware repository: grpc-ecosystem/go-grpc-middleware#559 (comment)

Is this a breaking change?
It's not.

[marcoshuck]

I consider creating a PR in a fork during the upcoming weekend.