Add implementation of ws_keyboard_send_keymap()

Suggested-by: Marcel Mueller <com2040@gmail.com>
Add implementation for ws_keyboard_send_enter()

Suggested-by: Marcel Mueller <com2040@gmail.com>
Prepare input device code for keyboard events

Suggested-by: Marcel Mueller <com2040@gmail.com>
Add implementation for get_resource()

Suggested-by: Marcel Mueller <com2040@gmail.com>
Add implementation for ws_keyboard_send_leave()

Suggested-by: Marcel Mueller <com2040@gmail.com>
Implement simple keyboard focus

Suggested-by: Marcel Mueller <com2040@gmail.com>
Add offset to event keycode

Suggested-by: Marcel Mueller <com2040@gmail.com>
Add deinit callback for ws_keyboard