Heavily revise the implementation of EventLoopConnectionPool (#102)

Author: gwynne

Package.swift

@@ -15,11 +15,15 @@ let package = Package(
     dependencies: [
         .package(url: "https://github.com/apple/swift-nio.git", from: "2.46.0"),
         .package(url: "https://github.com/apple/swift-log.git", from: "1.0.0"),
+        .package(url: "https://github.com/apple/swift-collections.git", from: "1.0.0"),
+        .package(url: "https://github.com/apple/swift-algorithms.git", from: "1.0.0"),
     ],
     targets: [
         .target(name: "AsyncKit", dependencies: [
             .product(name: "Logging", package: "swift-log"),
             .product(name: "NIO", package: "swift-nio"),
+            .product(name: "Collections", package: "swift-collections"),
+            .product(name: "Algorithms", package: "swift-algorithms"),
         ]),
         .testTarget(name: "AsyncKitTests", dependencies: [
             .target(name: "AsyncKit"),