refactor: move python scripts to code folder

1_single_job_step/README.md

1_single_job_step/single_job_step_parallel.sh

1_single_job_step/single_job_step_sequential.sh

2_multiple_job_steps/README.md

2_multiple_job_steps/multiple_job_steps.sh

2_multiple_job_steps/parallel_task.py

3_job_array/README.md

3_job_array/job_array.sh

3_job_array/job_array_task.py

code/parallel_task.py

code/sequential_task.py