change length_domain default convention to all axes in codomain

[ogauthe]

This PR changes the convention of length_domain and length_codomain to return all axes in the codomain by default. This convention matches TensorOperations.jl.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.16%. Comparing base (f9bdff5) to head (16def79).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #80   +/-   ##
=======================================
  Coverage   91.16%   91.16%           
=======================================
  Files          15       15           
  Lines         498      498           
=======================================
  Hits          454      454           
  Misses         44       44           

Flag	Coverage Δ
docs	0.00% <0.00%> (ø)

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.