[Docs]: MPPI and MPC path tracking

[mohitk3000]

Overview

This PR adds the documentation of the MPC and MPPI path tracking controllers, explaining the maths, code, optimization process, and a comparison of how MPC and MPPI work. Additionally some chore work on optimisation.

Changelogs:

• files added
  1. doc/4_path_tracking/4_2_mpc_controller.md
  2. doc/4_path_tracking/4_3_mppi_controller.md
• files modified:
  1. src/components/control/mppi/mppi_controller.py
     eariler np.linalg.inv(self.Sigma) was computed inside update() on every call even though Sigma never changes after construction. A minor optimisation is to compute it once in __init__ as self.Sigma_inv = np.linalg.inv(self.Sigma) and reference in the update().
  2. src/simulations/path_tracking/mpc_path_tracking/mpc_path_tracking.py
     added includes of warning module to suppress unnecessary warning of full version of do-mpc and some edit in comments

I have run both the MPPI and MPC path tracking controllers after these changes, and they are working as expected.

Checkpoints:

• Explanation of maths
• Explanation of code