Save allocations for bipartite graph with symmetric patterns

[gdalle]

• Add a symmetric_pattern kwarg to coloring, which can only be used for :nonsymmetric coloring problems. I didn't add this to GreedyColoringAlgorithm because it is not a property of the algorithm per se.
• Pass this kwarg to bipartite_graph and use it to save one allocation for the transpose of the sparse matrix. Even if this kwarg is false, also save the allocation whenever A isa Union{Symmetric,Hermitian}
• Add tests of column and row colorings on symmetric matrices.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (d8f579d) to head (c018181).
Report is 1 commits behind head on main.

Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files           10        10           
  Lines          729       732    +3     
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+ Hits           729       732    +3     

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