landing_gear_design: -Update src code to run nacelle clearance check inside of...

landing_gear_design:

• Update src code to run nacelle clearance check inside of the strut length dimensioning
• Add sub_function directory
• bugFixes for visualization of front view

Code tested with a converged CSMR-file for shifted nacelle position and nacelle position given from estimation -> both cases running like expected -> landing gear strut lengths will resized in each case -> nacelle ground clearance nacelle ground clearance is observed in each case