It is conventionally common for the X-Forwarded-For header to contain a
comma-separated list of IP addresses, with each intermediate proxy
adding an additional item as a request passes through it. This change
makes the web framework handle this case appropriately, always selecting
the first item in the list.
Moves/refactor Grafana specific functionality related to plugin dashboards
out to specific services for importing dashboards and keep app plugin dashboards
up-to-date.
Fixes#44257
