Add rotate_hindcast_logs worker

[douglatornell]

Call the doRollover() method on the RotatingFileHandler handlers of the run_NEMO_hindcast
logger.

This worker is intended to be launched from the command-line
by a nowcast administrator as necessary for maintenance of the hindcast log files
e.g. when a new hindcast is started, or when the logs from a running hindcast become annoying long.

[codecov]

Codecov Report

Merging #105 (dbf94de) into main (2ed245c) will increase coverage by 0.17%.
The diff coverage is 98.23%.

@@            Coverage Diff             @@
##             main     #105      +/-   ##
==========================================
+ Coverage   73.20%   73.37%   +0.17%     
==========================================
  Files         124      126       +2     
  Lines       16234    16347     +113     
  Branches     1319     1328       +9     
==========================================
+ Hits        11884    11995     +111     
- Misses       4299     4300       +1     
- Partials       51       52       +1     

Flag	Coverage Δ
unittests	73.37% <98.23%> (+0.17%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
nowcast/next_workers.py	98.36% <50.00%> (-0.27%)	⬇️
nowcast/workers/rotate_hindcast_logs.py	97.14% <97.14%> (ø)
tests/test_next_workers.py	99.71% <100.00%> (+<0.01%)	⬆️
tests/workers/test_rotate_hindcast_logs.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2ed245c...dbf94de. Read the comment docs.

[douglatornell]

Test in production was semi-successful:

• hindcast log files were successfully rotated
• "unregistered worker error" was raised because I forgot to restart manager
• realized that I did not write a next_workers.after_rotate_hindcast_logs() function