Grafana: add basic API Server graphs

[jkowalski]

QPS per resource type/verb:

sum(rate(apiserver_request_count[5m])) by (resource,verb)

Latency percentiles for key resource types:

apiserver_request_latencies_summary{resource=~"gameservers|fleets|pods",verb!~"WATCH|LIST",quantile="0.5"}

Error rates:

sum(rate(apiserver_request_count{code!~"2.."}[5m])) by (code)

Perhaps with a nice drop-down to allow narrowing it down by "resource" for common resource types (fleets, gameservers, pods, etc.)

[jkowalski]

Perhaps also have a dedicated graph to update conflict rate (HTTP 409):

sum(rate(apiserver_request_count{code="409"}[5m])) by (code,resource)

[cyriltovena]

There is already an API server graph do you want to improve it ?

[jkowalski]

We have a client view, this issue is about adding server-side view.

[aLekSer]

Hello @jkowalski , I can start adding these metrics.