There have been some reports of issue counts failing to calculate

correctly. The cause is not obvious, so we need better debugging.
This adds some debug logging to show all the calculation state for a

given review request's issues, which users can send us when they

encounter problems.
It also adds a reset-issue-counts management command, which will reset

issue counts for particular review requests, or all review requests if

passing --all.

Ran without any arguments. Saw an error.
Ran with a list of IDs. Saw it reset those counts.
Ran with --all. Saw it reset all IDs.
Ran with --recalculate --verbosity=2. Saw the debug output.
Verified these in the database.