HelpersImGui: use the standard ImGui backend for GLFW #1469

Job	Run time
Android (Ubuntu)	5m 11s
cmake-build-macos (macOS - Clang (Xcode), macos-latest, Debug, clang, clang++, Xcode, -DLVK_WITH_...	4m 6s
cmake-build (Windows - MSVC 2022 (glslang), windows-latest, Debug, cl, cl, Visual Studio 17 2022,...	3m 41s
cmake-build (Ubuntu - Clang (Wayland), ubuntu-latest, Debug, clang-16, clang++-16, Unix Makefiles...	3m 25s
cmake-build (Ubuntu - Clang, ubuntu-latest, Debug, clang-16, clang++-16, Unix Makefiles)	3m 38s
	20m 1s

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