Wish list: DruidSQL ability to query ALL servers

[vogievetsky]

Right now Druid has a sys.servers system table but that table could be infinitely more useful. Right now it only shows historical (and indexer-executor nodes) and only ones that are serving segments. It would be cool if this table was extended with more types and more columns.

Some suggestions:

• A server should appear in this list if it is part of the cluster.
• There should be more types (broker, router, coordinator, e.t.c)
• There should be more columns, one really cool one would be the druid version that each server is running so that we could see the the servers changing versions as a rolling update is going on.

Motivation:
Making the server table more powerful would turbo charge the servers view of the new Druid console

Right now the title of that view is "Data servers" but if this wish list item gets done we could make that view be called just "Servers"

[vogievetsky]

Done, yay