Create DatacenterAwareConfig to add Hosts in CQL Session Through ecc.yml

[VictorCavichioli]

Story Description:
Create new object in package com.ericsson.bss.cassandra.ecchronos.application.config.connection called DatacenterAwareConfig, it must represent the below configuration in ecc.yml:

connection:
  cql:
    datacenterAware:
      enabled: false
      datacenters:
      - name: datacenter1
        hosts:
        - host: 127.0.0.1
          port: 9042
        - host: 127.0.0.2
          port: 9042
        - host: 127.0.0.3
          port: 9042
        - host: 127.0.0.4
          port: 9042

connection.cql.datacenterAware.enabled must be false by default to avoid breaking the sidecar functionality; these described hosts will be added in the CQLSession on the application startup; in the a future task we'll create a new NativeConnectionProvider specific for the agent, which will be activated by the connection.cql.datacenterAware.enabled=true and connection.cql.provider=DatacenterNativeConnectionProvider.java, so to avoid future problems, expose the DatacenterAwareConfig in the NativeConnection.java class.

Acceptance Criteria:

• DatacenterAwareConfig Designed as Described;
• New TestConfig class created to specific Agent tests, also is proposed to change the old name of TestConfig to TestDefaultConfig or TestSidecarConfig;
• Architecture documentation updated with new topics.

Definition of Done:

Code tested and approved by maintainers.

Notes:

Related to #652

[VictorCavichioli]

After some discussions, we decided to change the configuration shape for the new below

agent:
      enabled: false
      type: datacenterAware
      contactPoints:
      - host: 127.0.0.1
        port: 9042
      - host: 127.0.0.2
        port: 9042
      datacenterAware:
        datacenters:
        - name: datacenter1
      rackAware:
        racks:
        - datacenterName: datacenter1
          rackName: rack1
      hostAware:
        hosts:
          - host: 127.0.0.1
            port: 9042
          - host: 127.0.0.2
            port: 9042
          - host: 127.0.0.3
            port: 9042
          - host: 127.0.0.4
            port: 9042