xclient.send_request() should just take a Request object and handle
to_bytes with the right byte order. This avoids typos/copy-paste errors
in tests when the byte order changes between tests.
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2216>
Add tests for commit b243ef9bc2 ("Xi: Swap property data in
SProcXChangeDeviceProperty/SProcXIChangeProperty").
Both tests set a format=32 property from a byte-swapped client and
read it back, verifying the values round-trip correctly. Without the
property data swap, the stored values have the wrong byte order.
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2187>