Add a few additional data points to logs.

[FGasper]

This adds:

• “Processing document comparison task” now mentions a) the namespace, and b) either the range’s min & max (gen0/check) or the # of documents (gen1+/recheck).
• “Finished document comparison task” now mentions the namespace.
• Logs for creation of recheck tasks now give the task ID.
• A new “Scheduled documents for recheck in the new generation” log that gives the total # and size of rechecks.

These data points would have been nice conveniences when reviewing logs for InfoMedia’s recent migration.

[tdq45gj]

LGTM