Refactor the kube-scheduler configuration API, command setup, and server
setup according to the guidelines established in #32215 and using the
kube-proxy refactor (#34727) as a model of a well factored component
adhering to said guidelines.
* Config API: clarify meaning and use of algorithm source by replacing
modality derived from bools and string emptiness checks with an explicit
AlgorithmSource type hierarchy.
* Config API: consolidate client connection config with common structs.
* Config API: split and simplify healthz/metrics server configuration.
* Config API: clarify leader election configuration.
* Config API: improve defaulting.
* CLI: deprecate all flags except `--config`.
* CLI: port all flags to new config API.
* CLI: refactor to match kube-proxy Cobra command style.
* Server: refactor away configurator.go to clarify application wiring.
* Server: refactor to more clearly separate wiring/setup from running.
Fixes#52428.
It currently is impossible to use two healthz handlers on different
ports in the same process. This removes the global variables in favor
of requiring the consumer to specify all health checks up front.
apiserver becomes kube-apiserver
controller-manager -> kube-controller-manager
scheduler and proxy similarly.
Only thing I promise is that right now hack/build-go.sh and
build/release.sh exit with 0. That's it. Who knows if any of this
actually works....
Dan Mace