[FEATURE] Add SSRS subscriptions that go to groups

[christopherpickering]

• [x] I've searched the issues
• [x] I've read the docs

Feature Request

Some subscriptions in this list:

select *
from dbo.ReportObjectSubscriptions
where userid is null

are to groups, not users. Right now it seems like those email addresses are not mapped to the group.

There are also a lot of blank records in there..