Add read-only process editor in the substation plugin

[JakobVogelsang]

As a user of OpenSCD I want to see Process element in the SCL in the substation plugin

Requirements

• make use of action-pnae
• title is "Process.name — Process.desc"
• show in all possible parents that is Process, SCL
• show all possible children, that is: ConductingEquipment, GeneralEquipment, Line, Substation, Process
• show all hidden children with showfunction=true that is Function, LNode

[pascalwilbrink]

I think this needs a new refinement. According to the SCD, process is not part of the Substation, but a sibling.
I don't think it would be logical to have the Process in the SubStation editor (?).
Should this be a new plugin?