GD-554: Adding support for touch screen input event testing to GdUnitSceneRunner

[MikeSchulze]

Why

see #554

What

• Stabilized the scene runner input buffer handling to avoid chaotic runtime errors
• Added new simulate touch screen functions

## Simulates a screen touch is pressed.[br]
## [member index] : The touch index in the case of a multi-touch event.[br]
## [member position] : The position to touch the screen.[br]
## [member double_tap] : If true, the touch's state is a double tab.
@warning_ignore("unused_parameter")
func simulate_screen_touch_pressed(index :int, position :Vector2, double_tap := false) -> GdUnitSceneRunner:


## Simulates a screen touch is press.[br]
## [member index] : The touch index in the case of a multi-touch event.[br]
## [member position] : The position to touch the screen.[br]
## [member double_tap] : If true, the touch's state is a double tab.
@warning_ignore("unused_parameter")
func simulate_screen_touch_press(index :int, position :Vector2, double_tap := false) -> GdUnitSceneRunner:


## Simulates a screen touch is released.[br]
## [member index] : The touch index in the case of a multi-touch event.[br]
## [member double_tap] : If true, the touch's state is a double tab.
@warning_ignore("unused_parameter")
func simulate_screen_touch_release(index :int, double_tap := false) -> GdUnitSceneRunner:


## Simulates a touch screen drag&drop to the relative coordinates (offset).[br]
## [color=yellow]You must use [b]await[/b] to wait until the simulated drag&drop is complete.[/color][br]
## [br]
## [member index] : The touch index in the case of a multi-touch event.[br]
## [member relative] : The relative position, indicating the drag&drop position offset.[br]
## [member time] : The time to move to the relative position in seconds (default is 1 second).[br]
## [member trans_type] : Sets the type of transition used (default is TRANS_LINEAR).[br]
## [codeblock]
##    func test_touch_drag_drop():
##       var runner = scene_runner("res://scenes/simple_scene.tscn")
##       # start drag at position 50,50
##       runner.simulate_screen_touch_drag_begin(1, Vector2(50, 50))
##       # and drop it at final at 150,50  relative (50,50 + 100,0)
##       await runner.simulate_screen_touch_drag_relative(1, Vector2(100,0))
## [/codeblock]
@warning_ignore("unused_parameter")
func simulate_screen_touch_drag_relative(index :int, relative: Vector2, time: float = 1.0, trans_type: Tween.TransitionType = Tween.TRANS_LINEAR) -> GdUnitSceneRunner:


## Simulates a touch screen drop to the absolute coordinates (offset).[br]
## [color=yellow]You must use [b]await[/b] to wait until the simulated drop is complete.[/color][br]
## [br]
## [member index] : The touch index in the case of a multi-touch event.[br]
## [member position] : The final position, indicating the drop position.[br]
## [member time] : The time to move to the final position in seconds (default is 1 second).[br]
## [member trans_type] : Sets the type of transition used (default is TRANS_LINEAR).[br]
## [codeblock]
##    func test_touch_drag_drop():
##       var runner = scene_runner("res://scenes/simple_scene.tscn")
##       # start drag at position 50,50
##       runner.simulate_screen_touch_drag_begin(1, Vector2(50, 50))
##       # and drop it at 100,50
##       await runner.simulate_screen_touch_drag_absolute(1, Vector2(100,50))
## [/codeblock]
@warning_ignore("unused_parameter")
func simulate_screen_touch_drag_absolute(index :int, position: Vector2, time: float = 1.0, trans_type: Tween.TransitionType = Tween.TRANS_LINEAR) -> GdUnitSceneRunner:


## Simulates a touch screen drop&drop to the absolute coordinates (offset).[br]
## [color=yellow]You must use [b]await[/b] to wait until the simulated drop is complete.[/color][br]
## [br]
## [member index] : The touch index in the case of a multi-touch event.[br]
## [member position] : The drag start position, indicating the drag position.[br]
## [member drop_position] : The drop position, indicating the drop position.[br]
## [member time] : The time to move to the final position in seconds (default is 1 second).[br]
## [member trans_type] : Sets the type of transition used (default is TRANS_LINEAR).[br]
## [codeblock]
##    func test_touch_drag_drop():
##       var runner = scene_runner("res://scenes/simple_scene.tscn")
##       # start drag at position 50,50 and drop it at 100,50
##       await runner.simulate_screen_touch_drag_drop(1, Vector2(50, 50), Vector2(100,50))
## [/codeblock]
@warning_ignore("unused_parameter")
func simulate_screen_touch_drag_drop(index :int, position: Vector2, drop_position: Vector2, time: float = 1.0, trans_type: Tween.TransitionType = Tween.TRANS_LINEAR) -> GdUnitSceneRunner:


## Simulates a touch screen drag event to given position.[br]
## [member index] : The touch index in the case of a multi-touch event.[br]
## [member position] : The drag start position, indicating the drag position.[br]
@warning_ignore("unused_parameter")
func simulate_screen_touch_drag(index :int, position: Vector2) -> GdUnitSceneRunner:


## Returns the actual position of the touch drag postion by given index
## [member index] : The touch index in the case of a multi-touch event.[br]
@warning_ignore("unused_parameter")
func get_screen_touch_drag_position(index: int) -> Vector2: