New exporter metrics for application server connections

[pirat013]

By using the sapcontrol command:
sapcontrol -nr -function GetAccessPointList

we can checks if the access points of the SAP instances can be retrieved using the Web service method.

It will also show the connections between all the application servers. Monitoring this connection can be used together with other metrics to check if a node is operational. It's maybe possible to draw a map with Grafana to identify some hot spots for connection entry points.