Making Darshan's code Neater, Modular & Faster

[MananTheCoder]

1. Currently, the evaluate_user function is quite lengthy. Can we bring out subfunctions out of this to give it a modular look? @Darshan-Padia
2. What are some possible values of return code for the following code snippet & can we quickly write some code that gives that return code.

   result = subprocess.run(
       "./temp_executable",
       stdin=infile,
       capture_output=True,
       text=True,
       timeout=1,
   )
   return result.stdout if result.returncode == 0 else None ```
   

3. Indent the logs
4. Add Multithreading for different users' evaluation, 1 thread per user.