proxy grpc request

[fenixnow]

---

I am faced with the problem of not being able to proxy a grpc request. When proxying, I caught the http2 extension error.

after poking around in the implementation, I saw that the plugin always proxies the request to an open text connection and no headers are passed to the request.

this fix fixes this issue.

based on assumptions, I use a typical .proxiedFrom() with http/s, which I use to determine the type of secure connection.

References

#61

Submitter checklist

• Recommended: Join WireMock Slack to get any help in #help-contributing or a project-specific channel like #wiremock-java
• The PR request is well described and justified, including the body and the references
• The PR title represents the desired changelog entry
• The repository's code style is followed (see the contributing guide)
• Test coverage that demonstrates that the change works as expected
• For new features, there's necessary documentation in this pull request or in a subsequent PR to wiremock.org