Add and use YouTube videos within the Slint docs #19779

Job	Run time
build_and_test (ubuntu-22.04, 1.82)	14m 14s
node_test (ubuntu-22.04)	3m 15s
build_and_test (macos-14, stable)	33m 15s
node_test (macos-14)	8m 47s
build_and_test (windows-2022, stable)	25m 50s
node_test (windows-2022)	6m 29s
build_and_test (windows-2022, 1.82)	16m 54s
python_test (ubuntu-22.04)	2m 7s
cpp_cmake (macos-14, 1.82)	8m 48s
python_test (macos-14)	1m 32s
build_and_test (windows-2022, beta, --exclude ffmpeg --exclude gstreamer-player)	23m 21s
cpp_cmake (windows-2022, nightly)	10m 32s
build_and_test (ubuntu-22.04, nightly)	18m 6s
python_test (windows-2022)	3m 33s
cpp_test_driver (ubuntu-22.04)	7m 42s
cpp_cmake (ubuntu-22.04, stable)	7m 37s
cpp_test_driver (macos-13)	8m 18s
cpp_test_driver (windows-2022)	9m 9s
ffi_32bit_build	1m 14s
mcu (pico-st7789, thumbv6m-none-eabi)	40s
mcu_esp	2m 49s
mcu (pico2-st7789, thumbv8m.main-none-eabihf)	59s
mcu (stm32h735g, thumbv7em-none-eabihf)	56s
vsce_build_test	6m 49s
android	1m 58s
esp-idf-quick	9m 26s
fmt_test	2m 12s
miri	50s
updater_test (0.3.0)	1m 39s
docs / docs	11m 5s
tree-sitter / tree-sitter-tests	12s
wasm / wasm	4m 57s
wasm_demo / wasm_demo	2m 53s
cpp_package_test	2m 16s
wasm / build-slintpad	1m 42s
	4h 22m 6s

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