Deprecate autosubmit support

[nextmat]

We currently support autosubmit_interval for Queue & `Aggregator, as described here.

Unfortunately there isn't a way to make this automatically submit at regular intervals without introducing a running loop or background thread (and handling related thread safety), both of which can introduce unexpected behavior in the host's code. For this reason the current implementation only checks if it should submit when it receives a measurement - when this happens rarely submission period can run well over the specified submit interval.

We've had a number of people reasonably confused by this behavior (likely the cause of #125) so I suggest we just drop it entirely since rolling your own version of this behavior is pretty trivial and much less confusing.

Autosubmitting based on measurement count autosubmit_count doesn't have this issue and should probably remain.