chore: split into packages

[Tahul]

The DocusGen org has been created and you all have been invited to it.

I also created a repository for each module that we need to split before releasing.

The objective is to get these:

• src/defaultTheme + src/i18n => https://github.com/docusgen/theme
  • @docus/theme
• src/app + src/settings => https://github.com/docusgen/docus
  • docus
• src/social-image => https://github.com/docusgen/social-image-module
  • @docus/social-image
• src/github => https://github.com/docusgen/github-module
  • @docus/github
• src/core => https://github.com/docusgen/api
  • @docus/api
• src/core/parser => https://github.com/docusgen/core
  • @docus/core
• src/admin => https://github.com/docusgen/admin
  • @docus/admin
• src/twitter => https://github.com/docusgen/twitter-module
  • @docus/twitter

This should be done after #520

During the resolving of #320 ; I will add a package boilerplate for each of these repositories, so once we begin to split these packages we keep a consistent structure across each repository.

Note that boilerplate will include the following:

• TypeScript
• ESLint + Prettier
• Build with Siroc
• Testing with Jest
• GitHub Actions
  • For testing
  • For releasing
• A Playground using the docus package and resolving the specific dependency locally