Added new GrowHorizontalLayout and GrowVerticalLayout widgets #770

Job	Run time
ios-sdl	1m 49s
android-sdl	6m 19s
android-sfml-graphics	3m 9s
ios-sfml-graphics	1m 12s
linux	9m 36s
linux-latest-dev	5m 38s
linux-oldest	4m 7s
linux-per-backend	5m 24s
macos	2m 5s
windows	3m 16s
windows-clang	5m 20s
windows-oldest	6m 22s
windows-static-mt	6m 14s
nightly-build-windows-visual-studio	6m 38s
	1h 7m 9s

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