Tests

Port of `ExternallyDereferenceable` to `OpenAPIKit30` module #924

Job	Run time
linux (swift:5.8-bionic)	1m 39s
osx	3m 16s
linux (swift:5.8-focal)	1m 32s
linux (swift:5.8-jammy)	3m 4s
linux (swift:5.8-amazonlinux2)	3m 10s
linux (swift:5.9-focal)	1m 48s
linux (swift:5.9-jammy)	1m 48s
linux (swift:5.9-amazonlinux2)	1m 56s
linux (swift:5.10-focal)	1m 44s
linux (swift:5.10-jammy)	1m 47s
linux (swift:5.10-amazonlinux2)	3m 22s
linux (swiftlang/swift:nightly-bionic)	3m 47s
linux (swiftlang/swift:nightly-focal)	2m 20s
linux (swiftlang/swift:nightly-jammy)	3m 59s
linux (swiftlang/swift:nightly-amazonlinux2)	2m 39s
	37m 51s

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