JP-3693: add MEDIUM-DEEP read pattern to schemas

[emolter]

Resolves JP-3693

Closes JWST 8662

This PR adds the new MEDIUM-DEEP readout pattern to the core schema as well as the readpatt and preadpatt schemas.

Checklist

• added entry in CHANGES.rst (either in Bug Fixes or Changes to API)
• updated relevant tests
• updated relevant documentation
• updated relevant milestone(s)
• added relevant label(s)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.21%. Comparing base (8b27b48) to head (9376300).
Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #315   +/-   ##
=======================================
  Coverage   66.21%   66.21%           
=======================================
  Files         101      101           
  Lines        5402     5402           
=======================================
  Hits         3577     3577           
  Misses       1825     1825           

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[emolter]

Not sure what is causing the test failures on main, but the ones here appear to match.

[braingram]

LGTM.