CMake modernization #1213

Job	Run time
Linux (clang, clang++, -DRMLUI_ENABLE_PRECOMPILED_HEADERS=OFF -DRMLUI_SAMPLES_BACKEND=GLFW_GL2)	2m 23s
Linux (clang, clang++, -DRMLUI_SAMPLES_BACKEND=SDL_VK)	3m 11s
Linux (-DRMLUI_BUILD_TESTING=ON -DRMLUI_ENABLE_PRECOMPILED_HEADERS=OFF, true)	2m 7s
Linux (-DRMLUI_ENABLE_LOTTIE_PLUGIN=ON -DRMLUI_SAMPLES_BACKEND=X11_GL2)	2m 12s
Linux (-DRMLUI_DISABLE_RTTI_AND_EXCEPTIONS=ON -DRMLUI_SAMPLES_BACKEND=SDL_GL2)	2m 2s
Linux (-DRMLUI_NO_THIRDPARTY_CONTAINERS=ON -DRMLUI_SAMPLES_BACKEND=SFML_GL2)	2m 5s
Linux (-DRMLUI_SAMPLES_BACKEND=SDL_VK -DRMLUI_VK_DEBUG=ON -DRMLUI_ENABLE_PRECOMPILED_HEADERS=OFF ...	2m 1s
macOS (-DRMLUI_SAMPLES_BACKEND=GLFW_GL2)	39s
Windows (-DRMLUI_SAMPLES_BACKEND=Win32_VK -DRMLUI_VK_DEBUG=ON -DVulkan_LIBRARY="C:\VulkanSDK\1.3....	11m 18s
Windows (-DRMLUI_SAMPLES_BACKEND=SDL_VK -DRMLUI_BUILD_LUA_BINDINGS_FOR_LUAJIT=ON -DVulkan_LIBRARY...	11m 9s
Emscripten	1m 3s
	40m 10s

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