Add `Rml::Element::Matches` function #1344

Job	Run time
Emscripten	2m 45s
Linux (clang, clang++, -DENABLE_PRECOMPILED_HEADERS=OFF -DSAMPLES_BACKEND=GLFW_GL2)	2m 21s
macOS (-DSAMPLES_BACKEND=auto)	4m 48s
Linux (clang, clang++, -DBUILD_TESTING=ON -DSAMPLES_BACKEND=SDL_VK -DCMAKE_BUILD_TYPE=Debug)	1m 45s
Linux-legacy (clang, clang++, -DENABLE_PRECOMPILED_HEADERS=OFF -DSAMPLES_BACKEND=GLFW_GL2)	1m 51s
macOS (-DSAMPLES_BACKEND=GLFW_GL2)	4m 30s
Linux (-DBUILD_TESTING=ON -DENABLE_PRECOMPILED_HEADERS=OFF, true)	2m 9s
Linux-legacy (clang, clang++, -DBUILD_TESTING=ON -DSAMPLES_BACKEND=SDL_VK -DCMAKE_BUILD_TYPE=Debug)	1m 27s
Windows (-DSAMPLES_BACKEND=auto -DENABLE_PRECOMPILED_HEADERS=OFF)	5m 31s
Linux (-DNO_FONT_INTERFACE_DEFAULT=ON -DENABLE_LOTTIE_PLUGIN=ON -DSAMPLES_BACKEND=X11_GL2)	1m 13s
Linux-legacy (-DBUILD_TESTING=ON)	1m 52s
Windows (-DSAMPLES_BACKEND=Win32_VK -DRMLUI_VK_DEBUG=ON)	6m 5s
Linux (-DDISABLE_RTTI_AND_EXCEPTIONS=ON -DSAMPLES_BACKEND=SDL_GL2)	1m 11s
Linux-legacy (-DSAMPLES_BACKEND=SDL_VK -DRMLUI_VK_DEBUG=ON -DENABLE_PRECOMPILED_HEADERS=OFF -DCMA...	1m 40s
Windows (-DSAMPLES_BACKEND=SDL_VK -DBUILD_LUA_BINDINGS_FOR_LUAJIT=ON)	5m 57s
Linux (-DNO_THIRDPARTY_CONTAINERS=ON -DSAMPLES_BACKEND=SFML_GL2)	1m 14s
Linux (-DSAMPLES_BACKEND=SDL_VK -DRMLUI_VK_DEBUG=ON -DENABLE_PRECOMPILED_HEADERS=OFF -DCMAKE_BUIL...	1m 31s
	47m 50s

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