Rename demo folder to project for generalizing the template usecase #19

Job	Run time
build (linux, x86_64, ubuntu-22.04, template_debug, double)	40s
build (macos, universal, macos-latest, template_debug, single)	38s
build (web, wasm32, ubuntu-22.04, template_release, double)	49s
build (android, arm64, ubuntu-22.04, template_debug, single)	1m 2s
build (windows, x86_64, windows-latest, template_release, single)	10m 19s
	13m 28s

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