feat(vector): Add help output for configurations with datadog_agent source

[spencergilbert]

Signed-off-by: Spencer Gilbert spencer.gilbert@datadoghq.com

Closes: https://github.com/vectordotdev/helm-charts/issues/177

NOTE: I've varied from the issue on the setting of DD_CONTAINER_EXCLUDE to use name instead of image to more gracefully handle users bringing their own images.

• [x] Detect when a datadog_source is configured
• [x] Output SSL config based on tls configuration
• [x] Parse address to get the port and build the url from that and the service name
• [ ] Stretch goal - get the load balancer/ingress name for the url if possible
• [ ] Handle multiple configured datadog_source components

I'd like to push the last two into separate issues - duplicate sources doesn't break the current implementation, it just prints out the values for one. The loadbalancer improvement will take some time with a real cluster

[spencergilbert]

As of 796a72a8377bcee74b9e80e8082fc248125e6880, the joutput (based on the datadog_quickstart.yaml) looks like this: