Shared Igniter upgrade logic for lifting actuator-driver reverse? options into per-attachment transmission blocks.

Used by the upgrade tasks in each driver package (Feetech, Robotis, PCA9685, Pigpio). The transformation is:

Before:

joint :shoulder do
  type :revolute
  limit do
    lower(~u(-10 degree))
    upper(~u(190 degree))
    effort(~u(10 newton_meter))
    velocity(~u(180 degree_per_second))
  end
  actuator :motor, {BB.Servo.Feetech.Actuator,
    servo_id: 1, controller: :feetech, reverse?: true
  }
  link :arm
end

After (with lift_offset?: true):

joint :shoulder do
  type :revolute
  limit do
    lower(~u(-10 degree))
    upper(~u(190 degree))
    effort(~u(10 newton_meter))
    velocity(~u(180 degree_per_second))
  end
  actuator :motor, {BB.Servo.Feetech.Actuator,
    servo_id: 1, controller: :feetech
  } do
    transmission do
      offset(~u(90.0 degree))
      reversed? true
    end
  end
  link :arm
end

The offset is computed as (lower + upper) / 2, preserving the auto-centering behaviour the Feetech/Robotis drivers used to derive internally. lift_offset?: false skips the offset computation — used by the PCA9685 and Pigpio upgraders, which never auto-centered.

Also handles re-running on code that was previously upgraded to put the transmission block at the joint level: such blocks are removed and merged into the actuator's own block.