[studio] Cluster status indication

[michaelvlach]

Indicate in the header status of the underlying server / cluster.

Endpoint is api/v1/cluster/status, poll every 10-30 seconds or on hover/click.

Response is list of server statuses that contain:

    pub address: String,
    pub status: bool,
    pub leader: bool,

If leader mark that server with a crown.

• If all status == false mark the overall status RED.
• If no leader or any of the servers is status == false mark the overall status AMBER.
• If all status == true and there is a leader mark the overall status GREEN.