Test-suite improvements.

[maleadt]

The most important change here is to rely on adapt(AT, x) instead of rolling our own adaptor that uses the array type constructor, since the former may have some more functionality registered with it. Specifically:

julia> x = view(rand(Float32, 100, 100), 2:99, 2:99);

julia> typeof(x)
SubArray{Float32, 2, Matrix{Float32}, Tuple{UnitRange{Int64}, UnitRange{Int64}}, false}

julia> x isa StridedArray
true

julia> struct ArrayAdaptor{AT} end

julia> Adapt.adapt_storage(::ArrayAdaptor{AT}, xs::AbstractArray) where {AT} = AT(xs)

julia> y = adapt(ArrayAdaptor{CuArray}(), x);

julia> typeof(y)
SubArray{Float32, 2, CuArray{Float32, 2, CUDA.DeviceMemory}, Tuple{CuArray{Int64, 1, CUDA.DeviceMemory}, CuArray{Int64, 1, CUDA.DeviceMemory}}, false}

julia> y isa StridedCuArray
false

julia> z = adapt(CuArray, x);

julia> typeof(z)
SubArray{Float32, 2, CuArray{Float32, 2, CUDA.DeviceMemory}, Tuple{UnitRange{Int64}, UnitRange{Int64}}, false}

julia> z isa StridedCuArray
true

This may also be a bug we need to fix in Adapt, but it seems fine to rely more on adapt(AT, x) anyway.