v2.4.0

• Introduced ListOfControls fixture to inspect controls in a window or running windows, and removed functions ListOfControls and ListOfControlsFromRoot from UiAutomationFixture
• Made the locator ":" return all controls
• Made TimeoutSeconds a static property and refactored it into ExtensionFunctions to eliminate proliferation of timeout values
• Made ProcessObject return null if HasExited is true
• Refactored UWPApplication and ClassicApplication to use common base class, and made UWP process detection more stable.
• Fixed flakiness in detection of UWP application activation
• Introduced SafeAppHandle in AppLauncher