Add mrest and multirest to Toolkit::GetElementsAtTime. Fixes #3850 #1638

Job	Run time
Copy the font files	5s
Set up and cache emscripten	8s
Build ubuntu-20.04-g++-10	5m 9s
Build ubuntu-22.04-g++-11	5m 3s
Build ubuntu-22.04-g++-12	5m 55s
Build ubuntu-20.04-clang-11	5m 34s
Build ubuntu-22.04-clang-12	6m 8s
Build ubuntu-22.04-clang-12	6m 22s
Build ubuntu-22.04-clang-12	6m 2s
Build ubuntu-22.04-clang-13	5m 49s
Build ubuntu-22.04-clang-14	5m 49s
Build ubuntu-22.04-clang-11	5m 59s
Build ubuntu-22.04-clang-15	5m 47s
Build macos-latest-xcode-15.4	3m 31s
Build macos-latest-g++-12	3m 59s
Build JS toolkit (nohumdrum, Building toolkit without humdrum, -c -H -M, verovio-toolkit.js*)	6m 36s
Build JS toolkit (light, Building toolkit without humdrum as light version, -c -H -l -M, verovio-...	6m 42s
Build JS toolkit (wasm, Building toolkit without humdrum as wasm, -c -H -w -M, veroviowasm, true)	5m 44s
Build JS toolkit (default, Building default toolkit with humdrum, -c -M, -hum.js)	9m 49s
Check settings for deployment	1s
Build documentation	28s
Deploy JS toolkit	1m 11s
Deploy documentation	13s
Skip deployment if set	0s
	1h 42m 4s

Provide feedback