Optimized coloring for specific matrix types

[gdalle]

There are some matrix types for which we can directly compute the optimal coloring, like (block-)banded matrices.

ArrayInterface.jl does this already but only for column coloring. We could reuse some of that code (if the license is right) and generalize it to other colorings (row, symmetric, bidirectional).

Related:

• Optimized decompression for specific matrix types #64