avatar: add an `envsetup.sh` script

function avatar {

  # avatar script.

  _AVATAR="${ANDROID_BUILD_TOP}/packages/modules/Bluetooth/android/pandora/test/avatar.sh"

  # only compile when needed.

  if [[ "$1" == "run" ]]; then

    m avatar avatar.sh PandoraServer tradefed

    _AVATAR="avatar.sh"

  fi

  # run avatar script.

  "${_AVATAR}" "$@"

}