ENH: Add `_MotorPrints` Inheritance to Motor Prints Classes

[Gui-FernandesBR]

What is the problem?

I'm seeing a lot of code repetition inside the private _MotorPrints class and similars.

Describe the solution you'd like

Make the same that was already did for the motor plots here #456.
This can be really easy to do, but consumes time and requires testing. Here is an outline of possible solutions of this issue:

• Create a rocketpy/prints/motor_prints.py file
• Verify which methods from the solid, liquid or hybrid motors prints could potentially be moved to the _MotorPrints
• Modify rocketpy/prints/solid_motor_prints.py
• Modify rocketpy/prints/hybrid_motor_prints.py
• Modify rocketpy/prints/liquid_motor_prints.py

Obs.: It is possible that you identify that no method can be moved to the parent class. That's ok, but we would need you to tell it in this issue so we can finish the issue.