ConfigUpdatesAsyncSequence - should it be Sendable or passed as sending?

[czechboy0]

Right now ConfigUpdatesAsyncSequence isn't marked as Sendable, and isn't being passed into the watch closures as sending, either. That can limit how it can be used in the adopter's business logic.

Should it be marked Sendable? That would require that its input AsyncSequence (the one created by a ConfigProvider) also needs to be Sendable. Or should it be passed as Sending?

@FranzBusch, thoughts?

[czechboy0]

Made it Sendable in #55