Merge with PinGroup for CoreLib Reactive

[tobyk]

Request to add a Merge node with pingroup to VL.Reactive in the corelib.
I would make a PR but don’t think the corelib is on github?

This is @Tebjans design from the chat

ReactiveMergePinGroup.vl (5.9 KB)

[lecloneur]

I think this does the same :