Add gateway endpoints for exporter disable request

[deepthidevaki]

Add gateway endpoint to disable an exporter by its id. We should also add a way to monitor the progress of the operation. To be discussed if we should reuse the endpoint for cluster (scaling, force configure etc..) or define a new one specific for exporting or a general configurations.

[deepthidevaki]

Currently we have two related endpoints

• actuator/exporting/ for pausing an resuming exporting
• actuator/cluster for monitoring cluster configuration changes and the topology

For the new endpoints for enabling and disabling exporters

Proposal 1

POST actuator/exporters/{exportId} to enable // Here we also have to specify which other exporer to initialize from
DELETE actuator/exporters/{exporterId} to disable. We are not technically deleting the exporter. It remains in the config.

Proposal 2

POST actuator/exporters/enable/{exporterId} // Here we also have to specify which other exporer to initialize from
POST actuator/exporters/disable/{exporterId}

Proposal 3

POST actuator/exporters/{exporterId} 
{
 state: "enabled"
 initializeFrom: "otherExporterId"
}

POST actuator/exporters/{exporterId} 
{
 state: "disabled"
}

Monitoring

Users can also monitor the state of exporters and also monitor when enabling or disabling request is completed.

Proposal 1

We can reuse the endpoint for the cluster
GET actuator/cluster that respond with the full ClusterConfiguration including the ongoing change.

Proposal 2

Define a new endpoint
GET actuator/exporting or GET actuator/exporters that respond with only relevant fields from ClusterConfiguration including the ongoing change.

If going with this approach, we have to decide what should be included in the response for GET actuator/cluster.

@npepinpe Any suggestions?