BitArrays should not be DenseArrays (#25858)
BitArrays should not be DenseArrays
BitArray has previously been subtype of DenseArray, making it defined as a StridedArray. However - BitArrays do not and can not support the `pointer` function. As such, they can never be passed to a C function in the same manner that all other StridedArrays can.
This patch makes `BitArray <: AbstractArray`. Surprisingly little breaks in our test set, but this is indeed massively breaking. Notably, most of the other changes required here were actually long-standing bugs that this change simply happened to uncover.
