Rewrite Proposal No. 2: Repo Restructure, Semver, Plugins

[nattadasu]

Description

This issue will be a proposal on how Ryuusei "pleases" developers by better folder structures and ability to install additional plugins from dedicated repo

Changes

1. Restructure repo to be "pythonic" as possible
2. Follow Semver convention for each releases, starts at 1.0.0
3. Add a way to download and manage additional plugins
4. Proper typing and resolve linting issues >:o
5. Use TOML based config system than using .env, so plugin can add additional credential input there
6. Move nattadasu/ryuuRyuusei to ryuuRyuusei/ryuuRyuusei
7. Change database system from TSV to SQL
8. Move dataclasses to specific models/ folder
9. On /myanimelist profile, prefer scraping MyAnimeList HTML than relying on Jikan to avoid unwanted err
10. Create 👏 tests 👏 for 👏 every 👏 modules
11. Create a template for issue and pull request
12. Create a documentation website/folder on how to run bot, usage, and developing plugin for the bot
13. Drop language support as it kinda overhaul maintainer capability
14. Implement video embed if a service has attached URL to YouTube on title showcase