CMake modernization #1216

Job	Run time
Emscripten	5m 6s
Linux (clang, clang++, -DRMLUI_ENABLE_PRECOMPILED_HEADERS=OFF -DRMLUI_SAMPLES_BACKEND=GLFW_GL2)	2m 44s
Linux (clang, clang++, -DRMLUI_SAMPLES_BACKEND=SDL_VK)	1m 57s
Linux (-DRMLUI_BUILD_TESTING=ON -DRMLUI_ENABLE_PRECOMPILED_HEADERS=OFF, true)	2m 55s
Linux (-DRMLUI_ENABLE_LOTTIE_PLUGIN=ON -DRMLUI_SAMPLES_BACKEND=X11_GL2)	2m 7s
Linux (-DRMLUI_DISABLE_RTTI_AND_EXCEPTIONS=ON -DRMLUI_SAMPLES_BACKEND=SDL_GL2)	2m 7s
Linux (-DRMLUI_NO_THIRDPARTY_CONTAINERS=ON -DRMLUI_SAMPLES_BACKEND=SFML_GL2)	2m 4s
Linux (-DRMLUI_SAMPLES_BACKEND=SDL_VK -DRMLUI_VK_DEBUG=ON -DRMLUI_ENABLE_PRECOMPILED_HEADERS=OFF ...	2m 35s
Windows (-DRMLUI_SAMPLES_BACKEND=Win32_VK -DRMLUI_VK_DEBUG=ON -DVulkan_LIBRARY="C:\VulkanSDK\1.3....	10m 51s
Windows (-DRMLUI_SAMPLES_BACKEND=SDL_VK -DRMLUI_BUILD_LUA_BINDINGS_FOR_LUAJIT=ON -DVulkan_LIBRARY...	12m 31s
macOS (-DRMLUI_SAMPLES_BACKEND=GLFW_GL2)	5m 29s
	50m 26s

Provide feedback