Where current implementation, and more specifically tests, rely on the
current time then replace that with the PSR-20 Clock from 298c13ac3b.
Applicable updates to the date filter and report scheduling calculation.
We should verify that schedule and audience users are active accounts,
and that we don't try to send report schedules either from/to them if
they aren't.
Allow adhoc tasks to implement this method, so they too can have
descriptive names for themselves. Default implementation added to
return the class name itself.
