Add API for extending windows during animations

Provides an API for windows to extend themselves outwards during
animations. In contrast to the scale animation the activity is not
distorted but rather the surface is extended outwards by the specified
amount without modifying the original window. The new "extension" space that is added is filled by clamping the edges of the surface. In the future the API could be extended to support different modes of filling the extension areas if required.

This API allows for the extension amount of the window to be animated
much like a scale or cliprect animation is, by providing a starting
amount for the extension and transitioning to the end amount by the end
of the animation.

This is required for the go/t-activity-transitions (https://direct.googleplex.com/#/spec/241720001&247800001) which we want to use as the default transition for T.

Test: atest CtsWindowManagerDeviceTestCases:AnimationEdgeExtensionTests
Bug: 202844659
Change-Id: Ic21e139fe329c271e71abdc6e77714c49365d5d6