Dust off configurations, update frontend and backend packages

[rnegron]

I want to get this repo in shape for potential new contributors... So I went ahead and tried to update some configurations while not changing anything about the implementation.

Additions

• Attempt to add Github CI with linting and test
  • Closes #11

Changes

• Remove yarn from READMEs and just use npm
  • npm is a lot better now that it used to be compared to yarn, trying to keep READMEs as simple as possible
• Remove .env from .dockerignore
  • need the .env inside the Docker volume
• Change Dockerfile based on some best practices
  • Using separate build stages, creating a non-admin user, etc
• Upgrade some Python packages where there were no real breaking changes
• Moved django-debug-toolbar into dev depedencies and moved it from Common configuration to Development configuration
• Changes to README files
  • Change SoPR Github links to Code4PuertoRico links
  • Streamlined some stuff like removing the MacPorts and yarn references
  • Typo fixes
• Added modern ESLint and Prettier support
• Updated frontend packages and also did minor updates for CDN dependencies: bootstrap and jquery
  • Re-did entire Webpack configuration using latest versions of all loaders and plugins
  • Closes #10

[rnegron]

@froi No tengo cómo asignar reviewers ni tampoco puedo merge al main repo 😢