use BlockedTuple in splitdims

[ogauthe]

Adapt BlockSparseArrays to the new TensorAlgebra.splitdims interface defined in ITensor/TensorAlgebra.jl#33

The new code removes the need for reducewhile.jl. I commented the include but did not delete the code as we may use it somewhere else or split it to its own library.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 24.79%. Comparing base (42ec520) to head (83c179a).
Report is 21 commits behind head on main.

Files with missing lines	Patch %	Lines
...sorAlgebraExt/BlockSparseArraysTensorAlgebraExt.jl	0.00%	5 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (42ec520) and HEAD (83c179a). Click for more details.

HEAD has 6 uploads less than BASE

Flag	BASE (42ec520)	HEAD (83c179a)
	6	0

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #55       +/-   ##
===========================================
- Coverage   75.15%   24.79%   -50.37%     
===========================================
  Files          30       29        -1     
  Lines        1111     1097       -14     
===========================================
- Hits          835      272      -563     
- Misses        276      825      +549     

Flag	Coverage Δ
docs	24.79% <0.00%> (+0.02%)	⬆️

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.

[ogauthe]

Closed as we now plan a new interface based on matricize / unmatricize