[robert3005]

ArrayOptimizer::optimize uses only the static rules of the encodings, so it misses the kernels that a session registers. This PR deprecates it, and array constructors no longer optimize the arrays they build.

Changes

• optimize_ctx and optimize_recursive take &impl AsOptimizerKernels, which is a VortexSession or an ExecutionCtx created from one. Existing optimize_ctx(&session) callers compile without changes.
• Constructors such as slice, filter, take, cast, fill_null, get_item and apply return lazy arrays. Execution optimizes each node it reaches (Optimize arrays bottom up and as execution reaches them #11090). Callers that read the encoding of an array directly now optimize it with their session first: scan tasks, plan v2 operators, the dict layout writer, the FFI scan and CUDA dispatch.
• The default append_to_builder optimizes the array first. It then appends through the encoding the array reduces to, so a lazy slice of a constant appends as a constant.
• Tests now call optimize_ctx(&SESSION) instead of optimize().

API Changes

• ArrayOptimizer::optimize is deprecated. Use optimize_ctx with the session or an ExecutionCtx.
• ArrayOptimizer::optimize_ctx and optimize_recursive are generic over AsOptimizerKernels.
• ArrayRef::slice, filter, take and the ArrayBuiltins methods no longer return an optimized array.