ci: Add `windows-ci-shared` that uses `vcpkg`. #179

Job	Run time
stable, macOS, shared library	45s
stable, macOS, static library	2m 25s
stable, Linux, static linking, no pkg-config	1m 28s
stable, iOS, static library	54s
stable, Linux, shared library	36s
stable, Emscripten, static library	1m 19s
stable, Windows, shared library	6m 31s
stable, Windows, static library	1m 34s
Result	0s
	15m 32s

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