Fix Windows HID backend missing byte

When the report id is zero, we should indeed skip the first byte of
transfer_priv->hid_buffer, since it is not part of the actual report.
But the report size should not change.

Thanks to Jonas Malaco who has done the investigation in this issue.
Reference: Jonas Malaco's comments
https://github.com/libusb/libusb/issues/902#issuecomment-810726897

Fixes #902
Fixes #977
Closes #986