Show collector configuration for a specific host/tag

## Context
At the Graylog UI you have no way to get the configuration visualized that is finally transmitted to the sidecar on a specific host. In bigger environments having multiple admins that can configure and change settings it would be useful to see which collector configurations will be finally transmitted to a sidecar.

It could also be useful to have the ability to check the transmission or spot errors by comparing the file on the server and the configuration in the UI.