Component Catalog Improvements

[jbuckner]

• Dark mode / light mode toggle
• Page font size slider
• Color scheme selector

[saurabhraghuvanshii]

Hi @jbuckner I want to work on this but before starting can I get more context about issue. thanks

[jbuckner]

@saurabhraghuvanshii appreciate your interest! We're currently undergoing some changes in the previews so adding this to my queue. Thanks!