Port of `ExternallyDereferenceable` to `OpenAPIKit30` module #929

Job	Run time
osx	4m 29s
linux (swift:5.8-bionic)	3m 15s
linux (swift:5.8-focal)	3m 17s
linux (swift:5.8-jammy)	3m 30s
linux (swift:5.8-amazonlinux2)	3m 25s
linux (swift:5.9-focal)	3m 41s
linux (swift:5.9-jammy)	3m 29s
linux (swift:5.9-amazonlinux2)	3m 41s
linux (swift:5.10-focal)	3m 38s
linux (swift:5.10-jammy)	3m 38s
linux (swift:5.10-amazonlinux2)	3m 34s
linux (swiftlang/swift:nightly-bionic)	3m 56s
linux (swiftlang/swift:nightly-focal)	4m 10s
linux (swiftlang/swift:nightly-jammy)	4m 0s
linux (swiftlang/swift:nightly-amazonlinux2)	4m 18s
	56m 1s

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