F# k8s deployment

[pbiggar]

This adds Apiserver to the kubernetes deployment. It's not yet hooked up to the ingress, so we're just testing that the server starts up.

• adds a container for F#
• adds an apiserver container based on it, which has debugging disabled,
• rename LibService/Healthcheck to LibService/Kubernetes
• add liveness, readiness, and startupprobe endpoints, running on their own ports
• handle shutdown on SIGTERM
• split legacyserver into legacy_serialization_server and legacy_fuzzing_server - this means the legacy_serialization_container doesn't need to connect to the DB
• add health checks and preStop to the fuzzing container

Misc:

• add notes to the coding guide
• fix path to gcp-proxy-db