This provides a better input experience via
simulate physical keyboard, it converts
SDL_KeyboardEvent to proper HID events and send it
via HID over AoAv2.
This is a rewriting and bugfix of the origin code
from [@amosbird](https://github.com/amosbird).
Make sdl_keymod_to_hid_modifiers() more readable
Support MOD keys in HID mode
Enable Ctrl+V on HID mode
Support to send media events from hid_keyboard
Use existing --serial to replace --usb
Use explict option for input mode
Move HID keyboard setup code into functions
Send HID events in separated thread
Let libusb handle max package size
Fix HID keyboard report desc
874a4967a4