refactor: extract materialized_artifact crate out of fspy #1349

Job	Run time
Format and Check Deps	26s
detect-changes	4s
Test (musl)	1m 4s
Clippy	35s
Test (namespace-profile-mac-default, x86_64-apple-darwin, cargo, x86_64-apple-darwin)	1m 7s
Test (namespace-profile-mac-default, aarch64-apple-darwin, cargo, aarch64-apple-darwin)	1m 7s
Test (namespace-profile-linux-x64-default, x86_64-unknown-linux-gnu, cargo-zigbuild, x86_64-unkno...	42s
Test (windows-latest, x86_64-pc-windows-msvc, cargo, x86_64-pc-windows-msvc)	1m 23s
done	3s
	6m 31s

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