Add contraction benchmarks

[lkdvos]

Introduces a benchmark suite for contractions, based on the contractions provided in:

Paul Springer: High-Performance Tensor Operations (Doctoral Thesis), RWTH Aachen University, 2018

(https://tensornetwork.org/benchmarks/)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.60%. Comparing base (4e5cc20) to head (007a1b7).
Report is 1 commits behind head on main.

Additional details and impacted files

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[mtfishman]

Very cool, thanks!

Just as a heads up, I have not focused on optimization at all yet, and I know we are missing certain optimizations (for example, we are not making use of the fact that certain contractions can be mapped to a transposed matrix multiplication, and in those cases are naively permuting the tensors).

[lkdvos]

I bumped the version, do you want to merge it so the registrator actions work?