Added new test input action, test scene and script with (currently
failing) tests for changes to simulation of global input state in
Godot 4.2, in which Input::ParseInputEvent() no longer sets
Input::IsActionPressed().

Updated action-input simulation extension methods to simulate global
input state in addition to events. Fixes behavior of StartAction()
and EndAction() to correctly set Input::IsActionPressed() in Godot
4.2.

Added new (currently failing) tests for
Input::IsActionJustPressed/Released(), which should be true
immediately after starting or ending an action, respectively.

To enable testing global input state immediately following inputs,
made action-input extensions synchronous, excepting HoldActionFor().
Tests for Input::IsActionJustPressed/Released() now pass.

BREAKING CHANGE: where possible, action-input methods are no longer
async, are void instead of returning Task, and have no frame delay.

BREAKING CHANGE: where possible, keyboard-input methods are no longer
async, are void instead of returning Task, and have no frame delay.

To make tests relying on mouse input more frame-accurate, made mouse-
input extensions synchronous. Set Relative property on simulated
mouse-motion events, since relative motion will no longer accumulate
in input buffer with immediate event flushing. Propagated
synchronicity to dependent driver methods and tests.

BREAKING CHANGE: mouse-input methods and many driver methods are no
longer async, are void instead of returning Task, and have no frame
delay.

To make tests relying on Control behavior more frame-accurate, made
control driver's GrabFocus() and ReleaseFocus() methods synchronous.

BREAKING CHANGE: Control driver's Grab/ReleaseFocus() methods are no
longer async, are void instead of returning Task, and have no frame
delay.

Make BaseButtonDriver::Press() synchronous and update dependent
tests.

BREAKING CHANGE: BaseButtonDriver::Press() is no longer async, is
void instead of returning Task, and has no frame delay.

Verified the return value of the Camera2DDriver::MoveIntoView()
method to ensure the camera stabilizes in its new position. Fixed
comment to reflect truth/falsity of sprite visibility.

BREAKING CHANGE: ItemList driver methods are no longer async, are
void instead of returning Task, and have no frame delay.

BREAKING CHANGE: LineEdit driver methods are no longer async, are
void instead of returning Task, and have no frame delay.

BREAKING CHANGE: OptionButtuon driver methods are no longer async,
are void instead of returning Task, and have no frame delay.

BREAKING CHANGE: PopupMenu driver methods are no longer async, are
void instead of returning Task, and have no frame delay.

BREAKING CHANGE: TextEdit driver methods are no longer async, are
void instead of returning Task, and have no frame delay.

BREAKING CHANGE: Window driver methods are no longer async, are void
instead of returning Task, and have no frame delay.

Updated description of WindowDriver::Close() to reflect that it
doesn't operate by clicking.

Also updated docs to reflect that Godot requires a frame after a tab
is selected before updating visibility of tab contents.

Also updated TabContainerDriver test to wait a frame after selecting
a tab, before checking content visibility, since the driver method no
longer has a frame delay.

BREAKING CHANGE: TabContainer driver methods are no longer async, are
void instead of returning Task, and have no frame delay.

* Changed code examples in README that no longer require async/await
* Updated description of input simulation to reflect synchrony
* Changed FAQ on asynchrony to describe it as a requirement only in
  some cases
* Pointed users toward the waiting extension examples from multiple
  other parts of README in case they need to pump frames in tests
* Removed guidance to limit state modification to the engine's
  process notifications
* Removed guidance to include frame delays in driver code, in favor
  of precise frame pumping in tests as needed

BREAKING CHANGE: Fixture::LoadScene() methods are no longer async,
return T instead of Task<T>, and have no frame delay.

Changed Fixture::AddToRoot() to wait 1 frame intead of 2 for a new
node's _Ready() to be called.

To provide a synchronous option to users, added a method to the
Camera2D driver to start moving a target position into view without
waiting for the camera's motion to finish.