chore(S2): audit style macro utilities

[reidbarber]

Exports:

• Exported all style macro utilities that are safe from breaking changes when design tokens or styles update. For the remaining utilities, we'll need to decide on a versioning system and come back to those later.
• Moved raw and keyframes exports to the @react-spectrum/s2/style sub-package only (since they're macros), and kept mergeStyles in the main @react-spectrum/s2 package only (it's runtime-only)
• Exported WidthProperties and HeightProperties as types for use with getAllowedOverrides

Renamed:

• Renamed colorScheme utility to setColorScheme to clarify that it sets the color-scheme property

Docs:

• Added JSDoc to all exported utilities
• Added a new "Utilities" section to the style macro reference docs documenting all exported utilities
• Updated the "Built-in utilities" section in the Styling guide to link to the new section in the style macro reference page

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

Verify the new exports and check the new JSDocs and docs additions.

🧢 Your Project:

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the S2 docs
• View the React Aria docs

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the S2 docs
• View the React Aria docs

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the S2 docs
• View the React Aria docs

[rspbot]

## API Changes

@react-spectrum/s2

/@react-spectrum/s2:getAllowedOverrides

+getAllowedOverrides {
+  undefined: any
+  returnVal: undefined
+}

/@react-spectrum/s2:centerPadding

+centerPadding {
+  minHeight: string
+  returnVal: undefined
+}

/@react-spectrum/s2:setColorScheme

+setColorScheme {
+  returnVal: undefined
+}

/@react-spectrum/s2:mergeStyles

+mergeStyles {
+  styles: Array<StyleString | null | undefined>
+  returnVal: undefined
+}

/@react-spectrum/s2:StylesProp

+StylesProp {
+  S: undefined
+}

/@react-spectrum/s2:StylesPropWithHeight

+StylesPropWithHeight {
+  S: undefined
+}

/@react-spectrum/s2:StylesPropWithoutWidth

+StylesPropWithoutWidth {
+  S: undefined
+}

/@react-spectrum/s2:UnsafeClassName

+UnsafeClassName {
+  U: undefined
+}

/@react-spectrum/s2:UnsafeStyles

+UnsafeStyles {
+  UNSAFE_className?: UnsafeClassName
+  UNSAFE_style?: CSSProperties
+}

/@react-spectrum/s2:StyleProps

+StyleProps {
+  UNSAFE_className?: UnsafeClassName
+  UNSAFE_style?: CSSProperties
+  styles?: StylesProp
+}

/@react-spectrum/s2:WidthProperties

+WidthProperties {
+  W: undefined
+}

/@react-spectrum/s2:HeightProperties

+HeightProperties {
+  H: undefined
+}

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