This test case uses `hidapi` -- a cross-platform Python module.
To keep the initial Mbed setup as simple as possible, the `hidapi`
module is skipped on Linux hosts because of its external dependancies
for this platform.
The module can be easily installed following instructions from the
README file.
The test case is skipped if the host machine lacks `hidapi` module.
Wait for the host driver to finish setup before sending any HID reports
from the device.
USBHID::wait_ready() blocks until the device reaches 'configured' state,
but the state of the host HID driver remains unknown to the device.