[rcore_web]: Fix Touch pointCount reduction

[maiconpintoabreu]

Issue:

1. Player touches position { 10, 10 } on the screen.

• CORE.Input.Touch.pointCount = 1
• Vector = [{10,10}]

2. Player touches position { 100, 100 } on the screen with another finger.

• CORE.Input.Touch.pointCount = 2
• Vector = [{ 10, 10 } , { 100, 100 }]

3. Player release first finger from position { 10, 10 }.

• CORE.Input.Touch.pointCount = 1
• Vector = [{ 10, 10 } , { 100, 100 }]

4. When the game try to access the position 0 it gets the wrong values as the Vector is not in order.

Solution:

1. Identify the index touch that was changed: if (touchEvent->touches[i].isChanged).
2. Move all touch values available one position up.
3. Reduce CORE.Input.Touch.pointCount.

[raysan5]

@maiconpintoabreu thanks for the detailed description of the problem and the provided fix!