Resolve conflicts in restructuring the script. Fixes #22

[mailology]

This is a new PR replacing the previous https://github.com/ThrunGroup/BanditPAM/pull/105. The fixes from the previous PR is applied on the latest main which solves the conflicts. Below are the fixes for restructuring the scripts:

• Create pam.cpp and banditpam.cpp which contain their own algorithm.
• Create driver script kmedoids_algorithm.cpp which implement the algorithms. The script contains all the functions from the previous kmedoids_ucb.cpp except the algorithms of PAM and BanditPAM.
• Update the src/CMakeLists.txt and setup.py to reflect the changes of the files.

I have tested the C++ and Python implementations of the code on MNIST-1k dataset. Both of them give expected results.

[motiwari]

Thanks @mailology ! I rebased this commit on top of main and merged it.