trying to update compat

[pat-alt]

• Removing to::CUDA.Adaptor everywhere and no longer typing this at all. CUDA.Adaptor seems to be deprecated but I can't find anything about it in docs.
• Removing NNlibCUDA since this seems to now by handled through an extension.

[chengchingwen]

1. CUDA.Adaptor is renamed as CUDA.KernelAdaptor after CUDA@5.1. Generally the overloading of adapt_storage already covers all the conversions. Overloading adapt(::Adaptor, ...) is a special case for using those masks directly in cuda kernel. However, I do think this design isn't that useful, so I might change it in the future.
2. Package extension is added after Julia v1.9. OTOH, this package tried to maintain the support of LTS version (which is v1.6 right now). I was waiting for a new LTS version and dropping v1.6 right after the new LTS release. Unfortunately, this doesn't seem to happen shortly, so we would probably need to maintain a new branch for Julia above v1.9.