Issues installing cvxpy dependency.

[allemangD]

Since cvxpy requires development tools be installed on the target machine, it is unsuitable for use in SlicerDWD. It's likely possible to build cvxpy in a superbuild for this module, however after spending some time researching this I've found it will be easier to simply use the existing GenDWD classifier as it does not depend on cvxpy.

See related discussion in https://github.com/slicersalt/dwd/issue/1.

To enable this I've integrated slicersalt/dwd#6, which makes cvxpy an optional dependency (installable via pip install dwd[socp]) and disables the DWD conic solver if it is not installed.

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Remaining work is to upgrade dwd to 1.0.5 in SlicerDWD, and port to the GenDWD classifier.