Docs - Add light theme and theme switch

[Madeline-UX]

Is your feature request related to a problem? Please describe.

Current docs only have dark theme configured.

Describe the solution you'd like

• Fix light theme in Docs
• Use MUI standards for background and paper
• Use same primary color
• Turn on theme switch
• Default dark theme (or browser default)

Describe alternatives you've considered

We could leave as is for branding purposes or wait until we decide if we are going to continue using Docusaurus

Additional context

Issue carried over from deprecated docs-site repo