Reuse external workflows in Fuzzer CI #96

Job	Run time
Build extension binaries / Generate matrix	23s
Build extension binaries / Linux (linux_amd64, ubuntu:18.04, x64-linux)	13m 25s
Build extension binaries / Windows (windows_amd64, x64-windows-static-md)	26m 9s
Build extension binaries / Linux (linux_amd64_gcc4, quay.io/pypa/manylinux2014_x86_64, x64-linux)	15m 12s
Build extension binaries / DuckDB-Wasm (wasm_mvp, wasm32-emscripten)	2m 10s
Build extension binaries / Windows (windows_amd64_rtools, x64-mingw-static)	37m 59s
Build extension binaries / Linux (linux_arm64, ubuntu:18.04, arm64-linux)	15m 52s
Build extension binaries / MacOS (osx_amd64, x86_64, x64-osx)	5m 16s
Build extension binaries / DuckDB-Wasm (wasm_eh, wasm32-emscripten)	2m 23s
Build extension binaries / DuckDB-Wasm (wasm_threads, wasm32-emscripten)	2m 14s
Build extension binaries / MacOS (osx_arm64, arm64, arm64-osx)	4m 13s
Deploy extension binaries	0s
	2h 5m 16s

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