Add `Max2Sequence` to be used in `ConnectionPool` (#419) #1036

Job	Run time
gh-codeql	7m 5s
linux-unit (swift:5.7-jammy)	3m 50s
api-breakage	0s
linux-unit (swift:5.8-jammy)	2m 49s
linux-integration-and-dependencies (postgres:16)	7m 59s
macos-all (postgresql@15, scram-sha-256, ~14.3)	3m 50s
linux-integration-and-dependencies (postgres:14)	11m 19s
linux-unit (swift:5.9-jammy)	3m 32s
macos-all (postgresql@15, scram-sha-256, ~15.0)	6m 23s
linux-integration-and-dependencies (postgres:12)	9m 55s
linux-unit (swiftlang/swift:nightly-5.10-jammy)	3m 51s
linux-unit (swiftlang/swift:nightly-main-jammy)	4m 3s
	1h 4m 36s

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