hidtools: Add support for BUS_HOST

Currently, hid-tools does not support BUS_HOST. This can, for example, cause hid-recorder to crash when it encounters a device with that bus with the following stack trace:

Traceback (most recent call last):
  File "/home/ukas/hid-tools/./hid-recorder", line 23, in <module>
    hidtools.cli.record.main()
  File "/usr/lib/python3/dist-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/usr/lib/python3/dist-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/lib/python3/dist-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/home/ukas/hid-tools/hidtools/cli/record.py", line 75, in main
    device_list = [open(list_devices())]
  File "/home/ukas/hid-tools/hidtools/cli/record.py", line 36, in list_devices
    d = HidrawDevice(f)
  File "/home/ukas/hid-tools/hidtools/hidraw.py", line 199, in __init__
    self.bustype = BusType(bustype)
  File "/usr/lib/python3.9/enum.py", line 360, in __call__
    return cls.__new__(cls, value)
  File "/usr/lib/python3.9/enum.py", line 678, in __new__
    raise ve_exc
ValueError: 25 is not a valid BusType

BUS_HOST is for example used on HID devices connected via the Microsoft Surface Aggregator, an embedded controller found on newer Microsoft Surface devices. On those devices the surface_hid kernel driver provides a HID transport channel to that EC.

Add support for BUS_HOST to prevent crashes like this.