[ENH] Remove dists_kernels

[TonyBagnall]

we currently have a module distances, which contains elastic distance functions, and one called dists_kernels that wraps everything in objects. I would like to remove dists_kernels. It is confusing having both, and I see no benefit from wrapping distances and introducing things like PwTrafoPanelPipeline, BasePairwiseTransformerPanel etc

I think this description would make little sense to most people.
https://www.sktime.org/en/stable/api_reference/dists_kernels.html

conceptually, insisting that functions be wrapped in objects (functor pattern) is much more Java like than python. Even java recognises functors are a clumsy pattern and introduced lambdas. To go the other way with python just seems perverse. @chrisholder can comment, but I believe all other relevant packages treat distances as functions.

#39
#46
https://arxiv.org/abs/2205.15181