Improvement: Refactor to individual modules per command

[mrzarquon]

Per: https://typer.tiangolo.com/tutorial/commands/context/

The POC phase left this codebase with all the logic inside the single cli.py file, as the features grow this should be broken up into individual modules for each command.

The main changes would be:
Move the remove the global data (watchlist / s) and replace with using contexts.
Instead of referencing this common data, just store and pass the arguments (or the parsed data?) as a context obj, which all the downstream modules would get. IE:

file: main.py

import typer
import subcommand

app.add_typer(subcommand.app, name="subcommand")

@app.callback(invoke_without_command=True)
def main(ctx: typer.Context, otherinput....):
  ctx.obj = parse(otherinput)

Then the subcommand, which only has one command itself:

file: subcommand.py
@app.callback(invoke_without_command=True)
def generate( ctx: typer.Context)
  parsed_configuration_from_main = ctx.obj

This doesn't make the subcommand stand alone, but would allow main.py --foo=bar subcommand to access foo in subcommand.py easily enough.

[mrzarquon]

Models were split apart here: #14