fix(ios): keep a keystroke from repeating what a textChange listener wrote - #11443

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
• You have signed the CLA.
• All existing tests are passing: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/DevelopmentWorkflow.md#running-unit-tests-application.
• Tests for the changes are included - https://github.com/NativeScript/NativeScript/blob/master/tools/notes/WritingUnitTests.md.

What is the current behavior?

On iOS, TextField.textFieldShouldChangeCharactersInRangeReplacementString computes the typed result, raises textChange through textProperty.nativeValueChange, and then returns true. If a textChange listener sets a different text inside that event, Property.set pushes the new value to the native field right away, and UIKit then inserts the typed character on top of it. Typing b into a field an uppercasing handler had left at A shows ABb while the property reads AB; a handler that resets or caps the value sees the rejected character appear anyway.

This is not framework-specific. Any integration whose state update runs synchronously inside the native event (Angular change detection in the zone task, Solid and Svelte signals, Octane, plain textChange handlers) hits it; integrations that flush asynchronously (Vue's scheduler, React 18 batching) instead see the caret jump to the end after the transformed write lands. Surfaced through nativescript-community/octane#3 while verifying a controlled-input fix there. TextView is unaffected because its delegate reports after the edit is applied, and Android's TextWatcher does too.

What is the new behavior?

After raising textChange, the delegate returns false when the listener wrote a different text: the setter has already put that value in the native field, so nothing is applied on top. The valueFormatter branch already worked this way. A listener that leaves text alone, or writes the same value, changes nothing (the write is a no-op in core and the delegate still returns true).

Tests

apps/automated gains typeCharacterNatively, which delivers one keystroke the way UIKit does (ask the delegate, apply the replacement only if it agrees; append on Android), and testTextWrittenByTextChangeListenerIsNotRepeatedByTheKeystroke, an uppercasing textChange listener typed a then b, asserting AB on both the property and the native field. It is gated to iOS since only that delegate can apply a keystroke after the listener ran.

Full automated iOS suite on the simulator: 1817 OK, 0 failed with the fix; with only the core change stashed, the same suite fails exactly this test (Actual: <AAB>), so it guards the regression.