feat(map-control): add className prop

[pudek357]

Summary

Adds an optional className prop to <MapControl> so users can style the control container element. Since MapControl renders its children into a detached <div> via createPortal (which is then handed to the Maps JavaScript API and positioned by the control-layout algorithm), there is currently no way for consumers to target that wrapping element from the React tree - the new prop closes that gap.

The implementation mirrors the existing className handling in sibling components (AdvancedMarker, InfoWindow): an effect syncs the prop to the DOM node as controlContainer.className = className ?? ''.

Changes

• src/components/map-control.tsx — add optional className prop and a useEffect that syncs it to the portal container.
• src/components/__tests__/map-control.test.tsx — add unit tests covering initial application, updates, and unset/removal of className.
• docs/api-reference/components/map-control.md — document the new prop under an "Optional" section.

Test plan

• npm run test:linter passes
• npm run test:prettier passes
• npm run test:tsc passes
• npm run test:unit -- map-control — 3/3 tests pass (1 existing + 2 new)
• Full npm run test:unit suite: no new failures introduced (pre-existing ts-jest failures on main are unrelated to this change)

Notes for reviewers

• No breaking changes; prop is optional and defaults to unset.
• API mirrors className on other components in the library for consistency.
• Happy to open a Discussion first if the maintainers prefer that flow for small additive props like this one — just let me know.