Add a new kernel transport driver (bthid) and bus driver (bthidbus)
to interface Bluetooth HID devices directly with the hid subsystem.

bthidbus exposes a character device interface allowing a userland
process to pass established sockets and device info to the kernel
via ioctl. bthid attaches to bthidbus as a child device, routing
incoming HID reports from the interrupt socket into hidbus.

Connection establishment (pairing, SDP querying) is handled entirely
in userland; this driver only takes ownership of already-connected
sockets.

This is currently a work in progress. I still need to implement a way for userspace to send commands to disconnect devices as well as detecting when devices disconnect.

Tested using a Nintendo Switch Pro Controller and Dualsense. Monitored inputs via evtest and testgamecontroller. The Switch Pro Controller successfully connects and uses the hgame driver. The Dualsense also connects and uses the hgame driver, but no inputs are actually detected. This is likely due to a mismatch between the report descriptor and the actual format of the packets being sent.