Remove `KeyOwned` #318

Job	Run time
test mdBook	38s
cargo test on ubuntu, rust stable	53s
cargo test on ubuntu, rust 1.78	1m 2s
cargo test on macos, rust stable	53s
cargo test on macos, rust 1.78	55s
cargo test on windows, rust stable	1m 44s
cargo test on windows, rust 1.78	1m 36s
	7m 41s

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