Fixes#1986
When deployed outside of the kubernetes cluster,
teleport now reads all configuration from kubernetes
config file, supplied via parameter.
Auth server then passes information about
target api server back to the proxy.
This commit moves proxy kubernetes configuration
to a separate nested block to provide more fine
grained settings:
```yaml
auth:
kubernetes_ca_cert_path: /tmp/custom-ca
proxy:
enabled: yes
kubernetes:
enabled: yes
public_addr: [custom.example.com:port]
api_addr: kuberentes.example.com:443
listen_addr: localhost:3026
```
1. Kubernetes config section is explicitly enabled
and disabled. It is disabled by default.
2. Public address in kubernetes section
is propagated to tsh profile
The other part of the commit updates Ping
endpoint to send proxy configuration back to
the client, including kubernetes public address
and ssh listen address.
Clients updates profile accordingly to configuration
received from the proxy.
