OHOS: Fix touch event processing to only handle the triggering finger

[bytemain]

Problem

The onNativeTouch callback was iterating through all touch points in touchEvent.touchPoints[] and sending SDL events for each one. However, this array contains the current state of all active fingers, not just the finger that triggered the current event.

This caused issues like:

• A single tap registering as multiple taps
• Touch events being duplicated for multi-touch scenarios

Solution

The OH_NativeXComponent_TouchEvent structure has an id field that identifies which finger triggered the current callback. We now find the matching touch point in the array using this ID and only process that single finger.

Changes

• Find targetIndex by matching touchEvent.touchPoints[i].id == touchEvent.id
• Only process the touch point at targetIndex instead of iterating all points
• Early return if no matching finger is found (defensive)

Testing

Tested on HarmonyOS device - single taps now correctly register as single events.