* add a metrics package to handle metric registration and publishing
* add a metricsAddress field to the server struct
* make metrics a part of the server
* start a metrics endpoint as part of starting the controllers
* instrument backup_controller to report metrics
* update cli-reference docs
* update example deployments with prometheus annotations
* update 'pkg/install' tooling with prometheus annotations
Signed-off-by: Ashish Amarnath <ashish.amarnath@gmail.com>