DM-53032: Add storage class / formatter for ExtendedPsfImage

[leeskelvin]

Checklist

• ran Jenkins
• added a release note for user-visible changes to doc/changes
• (if changing dimensions.yaml) make a copy of the updated dimensions.yaml in configs/old_dimensions and update the list in doc/lsst.daf.butler/dimensions.rst

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.61%. Comparing base (03e359c) to head (b9d42ea).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1371   +/-   ##
=======================================
  Coverage   89.61%   89.61%           
=======================================
  Files         373      373           
  Lines       50780    50780           
  Branches     5913     5913           
=======================================
  Hits        45509    45509           
  Misses       3880     3880           
  Partials     1391     1391           

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