[TensorAlgebra] Refactor contract

[mtfishman]

This refactors the contract function in TensorAlgebra based on refactored fusedims and splitdims functions for matricizing and unmatricizing.

It is based around a BlockedPermutation object which represents a permutation such as (2, 1, 4, 3) which is blocked or partitioned into parts, such as ((2, 1), (4, 3)). That is used to specify which dimensions of an array should get grouped together when performing a matricization of an n-dimensional array.

Basically ready, I still need to update definitions of fusedims and splitdims for NamedDimsArray where dimension names are used to specify matricization/dimension fusion.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (faa0357) 84.05% compared to head (027967c) 53.94%.
Report is 4 commits behind head on main.

❗ Current head 027967c differs from pull request most recent head 0368198. Consider uploading reports for the commit 0368198 to get more accurate results

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Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1290       +/-   ##
===========================================
- Coverage   84.05%   53.94%   -30.12%     
===========================================
  Files         100       99        -1     
  Lines        8542     8489       -53     
===========================================
- Hits         7180     4579     -2601     
- Misses       1362     3910     +2548     

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[mtfishman]

[test ITensors mps]

[github-actions]

Run ITensors mps tests from comment trigger: succeeded ✅
https://github.com/ITensor/ITensors.jl/actions/runs/7303340976

[github-actions]

Run ITensors mps tests from comment trigger: succeeded ✅
https://github.com/ITensor/ITensors.jl/actions/runs/7303340976