QUARKUS-278 - Test and verify Quarkus HTTP/2 support

JIRA link: https://issues.redhat.com/browse/QUARKUS-279

Coverage should ensure full HTTP/2 support from client and server side. For native mode similar test coverage as for JVM mode needs to be ensured.

Scope of the testing

Quarkus support by default HTTP/2 since version 1.4 (https://quarkus.io/blog/quarkus-1-4-final-released/), so the following action were taken to ensure test coverage:

Client Side:

Setup some scenarios in order to cover GRPC
Consume an HTTP/2 endpoint through quarkus-rest-client
Consume an HTTP/2 endpoint through quarkus-rest-client-mutiny

Server Side:

Verify that http/2 is set as default HTTP protocol
Consume and endpoint developed with quarkus-resteasy-jsonb through HTTP/2 Client (Vertx HTTP Client)

Impact on testsuites and testing automation:

Impact on resources:

More services will be running on OpenShift cluster, impact on CPU/memory should be minimal

Getting familiar with the feature

Following actions were taken to ensure familiarity:

Focus on exploratory testing of the features
Ensure good user experience and simplicity of use

Automated test development

This step should ensure:

Focus on high-level scenarios with multiple components and features involved
OpenShift should be the primary target platform for product to ensure good interoperability
Ensure platform specific features or components have appropriate test coverage