metadata_cache
==============

- added getters to metadata-cache-component

rest_metadata_cache
===================

Added REST endpoints

/metadata/
/metadata/{metadataName}/status
  - timeLastRefreshFailed
  - lastServerHostname
  - lastServerPort
/metadata/{metadataName}/config
  - clusterName
  - timeRefreshInMs
  - groupReplicationId
  - nodes

tests
=====

- added authentication support to rest_metadata_client

use REST endpoints of rest_metadata_cache to replace
fixed-time waits in compoment tests by polling REST endpoints

It reduces overall sequential test-suite runtime:

* from 144 seconds

RB:21742

Reviewed-by: Andrzej Religa <andrzej.religa@oracle.com>
Reviewed-by: Ulf Wendel <ulf.wendel@oracle.com>