Feat. Consolidate all stages into a single app

[danielcuthbert]

Currently there are 6 stages:

We should consolidate these into a single main.py and if needed, turn them into modules and call them accordingly, such as

from csvcleanse import (
process_row,
run_stage1
)

this makes it easier to update moving forward and makes the code cleaner

[capri-san]

Not sure if I understand what you mean. Right now each stage is a module, and we are importing all of them from tls_data_gatherer.py, which is our "main" or entry point to the application.