Implement image recovery system

[albireox]

This PR introduces a framework for recovering exposures that failed to write to disk.

During readout, once the buffer has been read and the header compiled, a lockfile is created with the same name as the final image + .lock. The lockfile contains the FetchDataDict with the exception of the data itself.

If an error prevents the image from being written, the lockfile can be used to recover the image. The ExposureRecovery class contains tools to update the lockfile and use it to recover the image.

During recovery, the lockfile is read and the buffer that contained the original data is fetched again. Wit that and the header from the lockfile it's possible to write the actual FITS file to disk.

Recovery happens automatically on the /data/.../MJD directory when the actor starts. It's also possible to trigger it manually with the recover command.

[codecov]

Codecov Report

Attention: 17 lines in your changes are missing coverage. Please review.

Comparison is base (cb47f85) 87.0% compared to head (1ca2a7e) 88.1%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
archon/actor/commands/expose.py	41.7%	4 Missing and 3 partials ⚠️
archon/actor/delegate.py	87.1%	5 Missing and 2 partials ⚠️
archon/actor/actor.py	90.0%	1 Missing and 1 partial ⚠️
archon/actor/recovery.py	99.2%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main     #47     +/-   ##
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+ Coverage   87.0%   88.1%   +1.2%     
=======================================
  Files         21      23      +2     
  Lines       1986    2160    +174     
  Branches     497     542     +45     
=======================================
+ Hits        1726    1901    +175     
+ Misses       171     167      -4     
- Partials      89      92      +3     

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