refactor: make login function's arguments required and not None

[sv0]

This pull request:

• moves arguments checking such as api_id, api_hash, api_phone_number to function main_entrypoint()
• makes command line option --phone-numbers required

Rationale:

• prepare a springboard for creating reusable pieces of code
  • e.g. I use this project as a library in pet-project(web based osint tool).

[GalenReich]

Thanks for the PR, separating out functionality like this is really sensible! I think it would be good to preserve the interactive option, but it should definitely move into main_entrypoint as you've done with the other arguments