Click execution fails on custom button due to incomplete pointer event sequence

### Description:

The problem is that the custom Button requires a specific sequence of pointer events to be fired for a click to register successfully. The custom button has strict validation checks in its OnPointerUp() method that are not currently being met.

For a click to be valid, the following conditions must be true:

1. isPointerInside must be true (which requires OnPointerEnter to be called first).
2. !isDragging and !eventData.dragging must be true.
3. pointerPress and raycast data must be properly set.

Currently, AltTester only executes the pointerUpHandler, which is insufficient to set the required state on the custom button.

### Proposed Fix:

To resolve this, AltTester must simulate the complete pointer event sequence: OnPointerEnter, OnPointerDown, and then OnPointerUp.

The following code demonstrates the required implementation:

```
var pointerEventData = new PointerEventData(EventSystem.current)
{
position = screenPosition,
button = PointerEventData.InputButton.Left,
eligibleForClick = true,
pressPosition = screenPosition,
pointerPress = eventSystemTarget,
pointerCurrentRaycast = new RaycastResult { gameObject = eventSystemTarget }
};

// Step 1: OnPointerEnter (sets isPointerInside = true)
ExecuteEvents.ExecuteHierarchy(eventSystemTarget, pointerEventData, ExecuteEvents.pointerEnterHandler);

// Step 2: OnPointerDown (sets required state for the click)
ExecuteEvents.ExecuteHierarchy(eventSystemTarget, pointerEventData, ExecuteEvents.pointerDownHandler);

// Step 3: OnPointerUp (now triggers the click successfully)
ExecuteEvents.ExecuteHierarchy(eventSystemTarget, pointerEventData, ExecuteEvents.pointerUpHandler);

```