Tests

Port of `ExternallyDereferenceable` to `OpenAPIKit30` module #923

Job	Run time
osx	1m 55s
linux (swift:5.8-bionic)	2m 59s
linux (swift:5.8-focal)	3m 1s
linux (swift:5.8-jammy)	1m 34s
linux (swift:5.8-amazonlinux2)	1m 40s
linux (swift:5.9-focal)	3m 18s
linux (swift:5.9-jammy)	1m 43s
linux (swift:5.9-amazonlinux2)	1m 57s
linux (swift:5.10-focal)	1m 48s
linux (swift:5.10-jammy)	1m 44s
linux (swift:5.10-amazonlinux2)	3m 24s
linux (swiftlang/swift:nightly-bionic)	2m 22s
linux (swiftlang/swift:nightly-focal)	2m 22s
linux (swiftlang/swift:nightly-jammy)	4m 0s
linux (swiftlang/swift:nightly-amazonlinux2)	4m 12s
	37m 59s

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