Add Rust API to grab the contents of a slint::Window into a slint::SharedImageBuffer #15548

Job	Run time
node_test (ubuntu-22.04)	2m 37s
build_and_test (ubuntu-22.04, stable)	13m 35s
build_and_test (ubuntu-22.04, 1.73)	15m 49s
build_and_test (macos-12, stable)	17m 0s
cpp_test_driver (ubuntu-22.04)	6m 24s
cpp_cmake (ubuntu-22.04)	6m 48s
build_and_test (windows-2022, stable)	20m 22s
cpp_test_driver (macos-12)	5m 7s
cpp_cmake (macos-12)	13m 9s
build_and_test (windows-2022, 1.73)	21m 5s
cpp_test_driver (windows-2022)	7m 17s
node_test (macos-12)	3m 32s
cpp_cmake (windows-2022)	7m 29s
build_and_test (windows-2022, beta, --exclude ffmpeg --exclude gstreamer-player)	21m 42s
node_test (windows-2022)	3m 30s
ffi_32bit_build	1m 0s
mcu (pico-st7789, thumbv6m-none-eabi)	44s
python_test (ubuntu-22.04)	1m 45s
mcu_esp	2m 22s
mcu (stm32h735g, thumbv7em-none-eabihf)	35s
python_test (macos-12)	1m 29s
uefi-demo	31s
python_test (windows-2022)	2m 6s
fmt_test	1m 43s
android	1m 49s
esp-idf-quick	8m 44s
miri	50s
updater_test (0.3.0)	1m 56s
docs / docs	7m 2s
wasm / wasm	4m 14s
wasm_demo / wasm_demo	17m 11s
tree-sitter / tree-sitter-tests	13s
wasm / lint-slintpad	23s
wasm / build-slintpad	46s
cpp_package_test	2m 45s
	3h 43m 34s

Provide feedback