Implement guidance around absolute position and degrees

[tthiery]

Knowledge dump

• TachoMotor.StartSpeedForDegreesAsync support moving the motor by degrees. It operates relative of its current position.
• AbsoluteMotor.GotoAbsolutePositionAsync allows moving the motor to an absolute position. It operates relative to a changeable zero position.
• The input mode 2 (POS) is reflecting the position relative to a changeable zero position (firmware in-memory encoded)
• The input mode 3 (APOS) is reflecting the position relative to marked zero position (physically encoded).
• POS is resetable with PortOutputCommandPresetEncoderMessage, APOS not.
• Technic(X)LargeLinearMotor / TechnicMediumHub do not remember their zero POS position.

Implementation

• Encode PortOutputCommandPresetEncoderMessage
• Add a AbsoluteMotor.GotoRealZeroAsync which moves the motor to align the position and the absolute position.
• Add a TachoMotor.SetZeroAsync allowing to reseting the zero value to the current position.
• Add comments to GotoAbsolutePosition and AbsolutePosition(Observable) explaining the behavior.