Dark mode setup themes

[shatfield4]

Pull Request Type

• ✨ feat
• 🐛 fix
• ♻️ refactor
• 💄 style
• 🔨 chore
• 📝 docs

Relevant Issues

resolves #xxx

What is in this change?

• Implement useTheme hook to allow switching of themes
• Implement ThemeProvider
• Add option to switch theme under appearance settings
• Setup tailwind generic classes to use in all our components
• Define custom theme definitions in index.css
• This setup creates a modular way of switching themes without making our main component css too messy
• Uses a generic tailwind class that is controlled by css variables

Additional Information

Developer Validations

• I ran yarn lint from the root of the repo & committed changes
• Relevant documentation has been updated
• I have tested my code functionality
• Docker build succeeds locally