Rule component: Adding new API end point for rules and alerts in

[davtsur]

Adding 2 new API end points for the rule component :

1. "api/vi/rules"
2. "api/vi/alerts"

Changes

1. Added 2 end points (based on prometheus rules end point)
2. Changed a few functions in the query API to be accessible and reused them in a new rule API class.
   Its also an option to add a common class for shared code of rule and query components, but I wasn't sure this is necessary.

Verification

1. Tested query and rule components locally
2. Added unitest for rule/alerts end points

[bwplotka]

I think we could put it in single v1 package for ease of use... But that's fine for now, LGTM!