inverse kinematics with FABRIK

Inverse kinematics using FABRIK, in 2d and 3d. Currently contains a third directory to build on top of that for multiple end effectors ## Single End Effector https://github.com/user-attachments/assets/c6d67798-022a-4d4d-942a-e1c6aae7fc56 ## Multi End Effectors https://github.com/user-attachments/assets/bf99e650-d458-4b1e-9ab1-5a7129cc44f4