[GradedAxes] Add dual and isdual

[mtfishman]

This adds a dual function for switching between contravariant and covariant spaces, and a function isdual to check if the space is contravariant or covariant. This is similar to the interface in TensorKit.jl.

@emstoudenmire @ogauthe

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (cef1c93) 84.05% compared to head (b3ab763) 53.92%.

❗ Current head b3ab763 differs from pull request most recent head e0962e8. Consider uploading reports for the commit e0962e8 to get more accurate results

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Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1274       +/-   ##
===========================================
- Coverage   84.05%   53.92%   -30.13%     
===========================================
  Files         100       99        -1     
  Lines        8540     8487       -53     
===========================================
- Hits         7178     4577     -2601     
- Misses       1362     3910     +2548     

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