Refactor bot.py

[luisgc93]

Just how the test suite was split into several modules, the same should probably be done for bot.py since the code is getting a bit spaghetti.

Some ideas of how it could be broken down:

• Modules for methods with outside API calls vs methods that don't have outside calls
• One module for each feature e.g. reply_mentions.py, publish_reminders.py, generate_report.py

[luisgc93]

It might make sense to follow a composition approach as in: https://github.com/luisgc93/chamath2cash/commit/9c9b706869e550b3caa82be97a2b33f1fa98b44c I.e. To create a Bot class that contains all the different clients plus some business logic.

[luisgc93]

WIP in branch refactor-with-composition-approach