Refactor matricize/unmatricize

[mtfishman]

Refactor matricize/unmatricize so that the core functionality doesn't depend on special types like BlockedTuple and BlockedPermutation so they are friendlier to overload for downstream packages.

Also, refactors the matricized contraction logic so the fusion style is computed ahead of time, stored in the algorithm type, and used in all calls to matricize and unmatricize.

Closes #95.

[codecov]

Codecov Report

❌ Patch coverage is 79.80769% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.89%. Comparing base (5c7a9bb) to head (1fb114f).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/matricize.jl	74.39%	21 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #96      +/-   ##
==========================================
- Coverage   92.27%   89.89%   -2.39%     
==========================================
  Files          16       16              
  Lines         492      554      +62     
==========================================
+ Hits          454      498      +44     
- Misses         38       56      +18     

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

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