x/build/cmd/gomote: configure HTTPS load balancers for the build infrastructure

[cagedmantis]

The gomote authentication revamp project requires Identity Aware Proxy to be enabled for the coordinator. As part of enabling IAP, an external HTTPS load balancer must be configured to route requests to our deployments on GKE. This is a multipart project which requires changing DNS addresses and various Kubernetes and GCP configuration changes.

This is a component of the project to revamp the security model used by gomote #47521
@golang/release

[gopherbot]

Change https://golang.org/cl/359234 mentions this issue: internal/https: document

[gopherbot]

Change https://golang.org/cl/359479 mentions this issue: cmd/coordinator,cmd/gerritbot: use HTTP/2 between LB and app

[gopherbot]

Change https://golang.org/cl/359480 mentions this issue: all: disable unnecessary serving methods

[gopherbot]

Change https://golang.org/cl/365735 mentions this issue: deploy: add GRPC servers to build.golang.org