chore: serve controller default metrics

[hectorj2f]

What this PR does / why we need it:

This PR exposes default controller metrics and makes both healthz-addr and metrics-addr configurable via flags.

rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="0.001"} 33
rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="0.002"} 156
rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="0.004"} 606
rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="0.008"} 1779
rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="0.016"} 2057
rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="0.032"} 2061
rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="0.064"} 2129
rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="0.128"} 2387
rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="0.256"} 2388
rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="0.512"} 2388
rest_client_request_latency_seconds_bucket{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET",le="+Inf"} 2388
rest_client_request_latency_seconds_sum{url="https://10.0.0.1:443/%7Bprefix%7D",verb="GET"} 34.46997236000008

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

In addition to this PR, I have prepared another work which adds kubefed custom metrics to certain actions which will give us a better view of future bottleneck of scalability issues.

[pmorie]

Thanks for doing this! LGTM, but you need to resolve the merge conflict first.

[hectorj2f]

@pmorie I rebased it against master. Thanks for taking a look at the PR.

[jimmidyson]

LGTM, with a note that this should migrate to use controller-runtime in future iterations imo.

[jimmidyson]

/lgtm
/approve

[jimmidyson]

/approve

[hectorj2f]

LGTM, with a note that this should migrate to use controller-runtime in future iterations imo.

@jimmidyson yeah, that would be awesome.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hectorj2f, jimmidyson

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