Add more bus diagnostics information

[martinboers]

Depending on the features of the controller, the following GDS Buffers may be available:

Component	Component ID	GDS Buffer ID
Axioline Controller Diagnostics	Arp.Io.AxlC	DiagVars
PROFINET Controller Diagnostics	Arp.Io.PnC	SysVars
PROFINET Device Diagnostics	Arp.Io.PnD	SystemVariables
INTERBUS-Master Diagnostics	Arp.Io.IbM	DiagVars
EthernetIP Diagnostics	Arp.Io.EthernetIP	STATUS

The variables in each buffer can be seen in the PLCnext Engineer global variable table for the device.