[Feature]: Update Vehicle Controller's Steering Calculations

[hellschwalex]

Description

Since we calculate Steering dually with the PurePursuit-Controller for lower and Stanley-Controller for higher velocities, the Vehicle Controller needs to newly assess the incoming Steering-Signals and decide on a final Steering signal internally.

• Overhaul currently implemented Sigmoid-Controller-Chooser-Function:
  • check other functions that allow more signal-mixing around the Cut-Off-Velocity, if that improves the total performance
  • check for the best Cut-Off-Velocity on newly implemented and tuned Controllers
• Overhaul the redundant, maybe useless PID-Controller for Steering-Input-Signals
  • check (after tuning both controllers) if PID improves performance, if not, delete it
  • check, if better performance, how PID can be tuned
  • if better performance, tune PID

Definition of Done

• Optimal Steering-Input processing in Vehicle Controller
• Unneccessary, redunant and overly complex concepts are either gone or well documented