lu_instance fails for JLArray #501

ArrayInterface.lu_instance fails for JLArray:

using JLArrays, ArrayInterface
ArrayInterface.lu_instance(jl(ones(3, 3)))
# ERROR: Illegal conversion of a JLArray to a Ptr

The GPUArraysCore extension builds the instance as
lu(Adapt.adapt(parameterless_type(A), ones(T, 0, 0))), and JLArrays has no lu of its own, so
that lands in LinearAlgebra's generic path. There is no size for which it works:

lu(jl(ones(0, 0)))   # Illegal conversion of a JLArray to a Ptr   (LAPACK getrf!)
lu(jl(ones(3, 3)))   # Scalar indexing is disallowed              (generic fallback)

so the 0x0 is not the issue, routing through lu is.

This bites test suites that use JLArrays as the stand-in for a GPU array on machines without
one. OrdinaryDiffEq reaches it from build_J_W and its GPU autodiff test is currently failing
on Julia 1, lts and pre.

Same shape as #467 for Metal. Would building the LU object directly be acceptable here rather
than calling lu?

ArrayInterface 7.29.0, JLArrays 0.3.2, GPUArraysCore 0.2.0, Julia 1.10.10.