Upgrade to Orleans 7?

[htxryan]

Hello! Is this project still alive? Are there any plans to upgrade to Orleans 7? Or is there an alternative pattern that should now be used?

If it's just a matter of capacity, I could take a first crack at a v7 upgrade PR.

[htxryan]

I went ahead and created a PR. It wasn't too difficult -- mainly had to add serializers for all message types. All tests are back to green. A few extension methods (and associated tests) were removed since AddApplicationParts() is no longer necessary in Orleans v7.