Add Fantom integration tests for core public APIs (#57466)

[rubennorte]

Summary:

Adds Fantom -itest.js coverage for maintained, public React Native APIs that were previously untested or thinly tested, driving both the JavaScript logic and the underlying cross-platform C++ through the public react-native package surface.

To make JavaScript-driven animations deterministic under the test runner, this also introduces a small timing indirection in Animated:

• New module Animated/AnimationTimingUtils.js exports getCurrentAnimationTime (returns Date.now() by default) and setAnimationTimeProvider (overrides the time source; pass null to restore the default).
• TimingAnimation, SpringAnimation and DecayAnimation now read the current time from getCurrentAnimationTime() instead of calling Date.now() directly. The default behavior is unchanged.

With this, a test can override the provider with a clock that advances one frame per read, which drives the JS-driver animation at the same cadence as the native frame clock. The spring and decay tests use this to verify the actual animation curve (overshoot for an underdamped spring, exponential deceleration for decay), not just the final value, and to run a single unified code path for both the JS and native drivers.

New test files:

• Animated/__tests__/SpringAnimation-itest.js, DecayAnimation-itest.js, AnimatedColor-itest.js, AnimatedComposition-itest.js — spring/decay curve shape (both drivers), Animated.Color value semantics, and the composition nodes (add/subtract/multiply/divide/modulo/diffClamp/tracking). AnimatedFantomTestUtils.js holds the shared trajectory helper.
• Components/View/__tests__/View-nativeCSSParsing-itest.js — string-valued CSS (color functions, transform, gradients) parsed via native CSS parsing.
• Pressability/__tests__/Pressability-touch-itest.js — press in/out/press, long press, press delay, and responder termination via touch events and the deterministic timer mock.
• Interaction/__tests__/PanResponder-itest.js — grant/move/release/terminate and gesture state across touch sequences.
• LayoutAnimation/__tests__/LayoutAnimation-itest.js — configureNext/create/presets applying the resulting layout.
• Network/__tests__/Network-itest.js — synchronous XMLHttpRequest lifecycle and validation.

Extended test files:

• Components/TextInput/__tests__/TextInput-itest.js — onSelectionChange/onSubmitEditing/onKeyPress/onEndEditing events.
• Lists/__tests__/FlatList-itest.js — onViewableItemsChanged across all viewabilityConfig options (itemVisiblePercentThreshold, viewAreaCoveragePercentThreshold, minimumViewTime, waitForInteraction).
• Text/__tests__/Text-itest.js — letterSpacing, lineHeight, and fontVariant styles.

The runtime behavior of Animated is unchanged; the new timing indirection defaults to Date.now().

Changelog:
[Internal]

Differential Revision: D110784436

[meta-codesync]

@rubennorte has exported this pull request. If you are a Meta employee, you can view the originating Diff in D110784436.