Python: Add support for direct .slint file imports #14091

Job	Run time
python_test (ubuntu-22.04)	1m 34s
python_test (macos-11)	2m 45s
cpp_test_driver (ubuntu-22.04)	5m 23s
cpp_cmake (ubuntu-22.04)	6m 31s
node_test (ubuntu-22.04)	3m 5s
python_test (windows-2022)	4m 21s
cpp_cmake (macos-12)	14m 44s
cpp_test_driver (macos-12)	6m 22s
node_test (macos-11)	5m 44s
cpp_cmake (windows-2022)	8m 10s
cpp_test_driver (windows-2022)	6m 46s
node_test (windows-2022)	5m 0s
build_and_test (ubuntu-22.04, stable)	9m 5s
build_and_test (ubuntu-22.04, 1.70)	9m 54s
ffi_32bit_build	1m 16s
mcu (pico-st7789, thumbv6m-none-eabi)	41s
build_and_test (macos-11, stable)	19m 15s
mcu_esp	2m 22s
mcu (stm32h735g, thumbv7em-none-eabihf)	38s
build_and_test (windows-2022, stable)	9m 11s
uefi-demo	46s
build_and_test (windows-2022, 1.70)	8m 34s
build_and_test (windows-2022, beta, --exclude ffmpeg --exclude gstreamer-player)	7m 59s
android	1m 16s
esp-idf-quick	8m 39s
miri	45s
fmt_test	1m 24s
updater_test (0.3.0)	1m 19s
docs / docs	6m 36s
tree-sitter / tree-sitter-tests	14s
wasm / wasm	3m 39s
wasm_demo / wasm_demo	13m 29s
wasm / lint-slintpad	27s
wasm / build-slintpad	50s
cpp_package_test	2m 33s
	3h 1m 17s

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