refactor: convert AnyOfField from class to functional component (#5139)

* refactor(core): convert AnyOfField from class to functional component

Replaces the class-based AnyOfField with a functional component using
useReducer for state management. State snapshots (prevOptions, prevFormData,
prevFieldId) replace the three useRef prev-trackers and useEffect, using
React's getDerivedStateFromProps render-phase dispatch pattern instead —
React re-renders immediately from those dispatches and discards the current
render before any DOM commit. onOptionChange is wrapped in useCallback.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* refactor(core): simplify AnyOfField state — useMemo + useState + useEffect

Replaces the render-phase dispatch pattern (getDerivedStateFromProps) with
conventional hooks: retrievedOptions moves to useMemo (pure derivation from
options/formData/schemaUtils), selectedOption becomes plain useState, and the
auto-matching logic returns to a post-render useEffect mirroring
componentDidUpdate. Removes AnyOfFieldState, AnyOfFieldAction, and
anyOfFieldReducer entirely. Including formData in useMemo deps also fixes a
latent bug where retrieved option schemas could be stale for formData-
conditional $refs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* - Replaced Object.is() comparison of `formData` with string comparison

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Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: heath-freenome