feat: provide prefixes definition in the overlay file

[candleindark]

These prefixes are copied from
https://github.com/dandi/schema/blob/master/releases/0.7.0/context.json

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.91%. Comparing base (c78f9d3) to head (aa0478f).
⚠️ Report is 2 commits behind head on linkml-auto-converted.

Additional details and impacted files

@@                  Coverage Diff                   @@
##           linkml-auto-converted     #383   +/-   ##
======================================================
  Coverage                  97.91%   97.91%           
======================================================
  Files                         18       18           
  Lines                       2401     2401           
======================================================
  Hits                        2351     2351           
  Misses                        50       50           

Flag	Coverage Δ
unittests	97.91% <ø> (ø)

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