LRAMetricService should be wrapped with its own JAX-RS resource

In rts/lra/test/basic, Arquillian test classes are annotated with @RunAsClient. As a consequence, the CDI is not available for test classes. As LRAMetricService needs to be injected (as a singleton) in lra-participants, a JAX-RS resource exposing some REST endpoints to query LRAMetricService can be considered instead of adding these endpoints to every single lra-participant.

Note: REST endpoints exposing LRAMetricService have been already wrote in the NestedParticipant. So, this JIRA would consist in wrapping these endpoints in a "supporting" class, which should be deployed through rts/lra/test/basic/src/test/java/io/narayana/lra/arquillian/Deployer where needed (e.g. NarayanaParticipantIT)