cmd/k8s-operator: generate static kube manifests from the Helm chart. (#10436)

* cmd/k8s-operator: generate static manifests from Helm charts

This is done to ensure that there is a single source of truth
for the operator kube manifests.
Also adds linux node selector to the static manifests as
this was added as a default to the Helm chart.

Static manifests can now be generated by running
`go generate tailscale.com/cmd/k8s-operator`.

Updates tailscale/tailscale#9222

Signed-off-by: Irbe Krumina <irbe@tailscale.com>

cmd/k8s-operator/operator.go

@@ -42,6 +42,8 @@ import (
 	"tailscale.com/version"
 )
 
+//go:generate go run tailscale.com/cmd/k8s-operator/generate
+
 func main() {
 	// Required to use our client API. We're fine with the instability since the
 	// client lives in the same repo as this code.