`Device.ctrl_transfer` depends on `create_buffer` raising a `TypeError`
if its parameter is not a valid length. In particular, if an array is
passed in, `create_buffer` must *not* return a copy of it.

Commit 3ea79b0 accidentally broke this and, consequently, any calls
to `ctrl_transfer` passing in a buffer. Thanks @kauwua for reporting the
issue and discussing the potential solutions.

Note that `length * b'\x00'` is actually faster than `bytes(length)`
(tested with Python 3.13 on x86_64).

Fixes: #528
Fixes: 3ea79b0 ("util: remove left over python 2 compatibility workaround")

While discussing #527, @kauwua made the valid point that we could
optimize for the case where the user has passed in a byte `array`.

In that spirit, prioritize the no-op conversion case, but also accept
the parameter to be a length for a new array in preparation for
replacing the conditional in `Device.ctrl_transfer`.

Related: #528

Optimize for the case where `data_or_wLength` is already a byte `array`,
as suggested by @kauwua in #527.

Related: #528