Add Halley's method via descent API

[tansongchen]

Add Halley's method by computing Hessian-vector-vector product with TaylorDiff.jl in $O(n)$ time. Note that this isn't structured as something like "HessianCache", but instead structured as a descent method, which can be viewed as "adding some correction term to the Newton's method". This is mainly because Hessian, either implicitly or explicitly, isn't likely to be used elsewhere.

Tests haven't been added because TaylorDiff.jl should be added to an extension. Once that is done, it is straightforward to add tests.

Checklist

• [x] Appropriate tests were added
• [x] Any code changes were done in a way that does not break public API
• [x] All documentation related to code changes were updated
• [x] The new code follows the contributor guidelines, in particular the SciML Style Guide and COLPRAC.
• [x] Any new documentation only uses public API

Additional context

Add any other context about the problem here.