Create new subscriptions when existing subscription is full

[marcschier]

Subscriptions are limited in size, and adding additional subscribers to an existing subscription might not be possible when the number of monitored items exceeds a server limit. We need to have a way to split subscriptions or start new ones and differentiate between which is owned by which.

Initially we use a command line option to set a max per publisher, as well as look at the server capabilities returned by the server.

Future items on the backlog.

• Enable an option to force the 2.9.11 and earlier behavior of writer per (physical) subscription. #2338
• Repartition with good count as max when any item has Bad_TooManyMonitoredItems status  #2339
• Create a new session when the max number of subscriptions per session are reached. #2340