Evaluate StyleX as a styling solution

[Niznikr]

Analyze tradeoffs/DX of StyleX to see how it compares to Vanilla Extract in terms of DX, TypeScript support, and box component implementation.

[Niznikr]

Notes from #1100

Size

Positives ✅

• Styles are co-located with component code
• Atomic by default which will ensure the size of the single stylesheet for the all-encompassing components package is minimal
• No specificity issues since the last style applied always "wins"
• Type-safe and provides a lint plugin
• The defineVars function (needed to use our tokens in a type-safe way with StyleX styles) hashes our custom properties enabling us to flag tokens

Trade-offs ⚖️

• Tokens defined in tokens.stylex.ts must be static (we can't import them from our tokens package), requiring us to generate the file using Style Dictionary
• No utilities offered for variants which VE has
• Box implementation TBD (likely using the static types)

[Niznikr]

Decided to continue with Vanilla Extract due to limitations identified in #1124