Add ModelOwner field to ARMs

[ibaldin]

In order to properly find which aggregate owns a particular model we need an explicit designation at least on some nodes of ARM who originally created this model. This needs to be carefully handled when the models are merged on stitch nodes, but it will help finding e.g. who the owner of the network model is when three-way merges (like EDC+NCSA+Network Model) are done.

[ibaldin]

How are we getting around this now? Just so I know how to test @kthare10 ?

[kthare10]

This is typically an issue for sites like EDC and NCSA which share a switch which results in the merged model to have multiple network delegation id and no way for the code to know the owner of the delegation id.

The current hack is to look for L3 Service in the the Switch and use it's delegation id.