Add extension-template-rs based demo extension #553

Job	Run time
prepare	3s
build / Generate matrix	2s
build / Windows (windows_amd64, x64-windows-static-md)	5m 43s
build / DuckDB-Wasm	0s
build / MacOS (osx_amd64, x86_64, x64-osx)	2m 34s
build / Linux (linux_amd64, ubuntu:18.04, x64-linux)	5m 42s
build / MacOS (osx_arm64, arm64, arm64-osx)	2m 32s
build / Linux (linux_amd64_gcc4, quay.io/pypa/manylinux2014_x86_64, x64-linux)	4m 6s
build / Linux (linux_arm64, ubuntu:18.04, arm64-linux)	5m 36s
doc_test / docs	7s
deploy / Generate matrix	26s
archive	0s
deploy / Deploy (linux_amd64)	30s
deploy / Deploy (linux_amd64_gcc4)	31s
deploy / Deploy (linux_arm64)	31s
deploy / Deploy (osx_amd64)	32s
deploy / Deploy (osx_arm64)	31s
deploy / Deploy (windows_amd64)	30s
deploy / clean_cache (osx_amd64) / Clean Caches	4s
deploy / clean_cache (linux_amd64) / Clean Caches	7s
deploy / clean_cache (linux_arm64) / Clean Caches	4s
deploy / clean_cache (linux_amd64_gcc4) / Clean Caches	3s
deploy / clean_cache (osx_arm64) / Clean Caches	6s
deploy / clean_cache (windows_amd64) / Clean Caches	4s
docs_all	0s
	30m 24s

Provide feedback