feat(code-snippet): Add tabs

[ArthurKnaus]

• Add tabs to the CodeSnippet component
• Restyle header so it has the same background as the snippet itself

Dark theme:

Light theme:

Light theme (dark=true):

[vuluongj20]

Rather than using raw values, why don't we use prism variables (--prism-base for text, --prism-comment for subtext, and --prism-highlight-accent for borders)? That way, we don't have switch between dark and light colors based on the dark prop (L110 below) — it's already handled via the prism-dark class name on <Wrapper /> (L113 below).

[ArthurKnaus]

I had it like this in my initial implementation but thought that it could be confusion as --prism-comment has a clear semantic meaning.
E.g. if someone changes the comments to be green they would expect the tab text to change too. 🤔

However, for the sake of shipping value I will change it to your proposition and merge it.
Maybe there is a better suited variable or we introduce a new one in the future?

[vuluongj20]

yeah it's not ideal, but I think it's preferable to using raw values since if in the future we change the colors in the design system we'll likely forget to also change it here.