VirtualKeyboard: Virtual Keyboard show/hide Fires Event & updates CSS env variables

Test Description: This test checks that a geometry change event is fired when show/hide APIs are called & also updates the CSS env variables for keyboard insets. VK is only displayed on a touch device with tablet mode on or a mobile device where VK is the default text input mechanism.

THIS IS A MANUAL TEST

Manual policy show here.
Read-only region tap here.