feat(Input) Add keys/mappings used by CEC

[addmix]

Implements a handful of keycode which are used by CEC input devices.

The new keycodes implemented are:
KEY_OK, KEY_EXIT, KEY_INFO, KEY_ROOT_MENU, KEY_RED, KEY_GREEN, KEY_YELLOW, KEY_BLUE
With the corresponding names in InputPlumber:
KeyOk, KeyExit, KeyInfo, KeyRootMenu, KeyRed, KeyGreen, KeyYellow, KeyBlue

The mapping for these keys are:

KeyOk: Gamepad South
KeyExit: Gamepad East
KeyInfo: Gamepad QuickAccess
KeyRootMenu: Gamepad Guide
KeyUp: Gamepad DPadUp
KeyDown: Gamepad DPadDown
KeyLeft: Gamepad DPadLeft
KeyRight: Gamepad DPadRight
KeyRed: Gamepad Select
KeyGreen: Gamepad Start
KeyYellow: Gamepad North
KeyBlue: Gamepad West

One aspect that I assume will need to be expanded is the source device matching.

Currently, devices are matched by name with the wildcard: DP-* (Corresponding to the graphic device's port numbering). This works for my case where I am using a UGREEN DisplayPort/HDMI adapter, but I assume it will not match for native HDMI-CEC, or Pulse8 adapters. If others with this hardware could test and contribute those matches, it would be appreciated.

source_devices:
  - group: keyboard
    udev:
      subsystem: input
      attributes:
        - name: name
          value: "DP-*"