Enable MemberImportVisibility check on all targets (#107)

Enable MemberImportVisibility check on all targets. Use a standard
string header and footer to bracket the new block for ease of updating
in the future with scripts.

Package.swift

@@ -154,3 +154,14 @@ var package = Package(
 
     cxxLanguageStandard: .cxx11
 )
+
+// ---    STANDARD CROSS-REPO SETTINGS DO NOT EDIT   --- //
+for target in package.targets {
+    if target.type != .plugin {
+        var settings = target.swiftSettings ?? []
+        // https://github.com/swiftlang/swift-evolution/blob/main/proposals/0444-member-import-visibility.md
+        settings.append(.enableUpcomingFeature("MemberImportVisibility"))
+        target.swiftSettings = settings
+    }
+}
+// --- END: STANDARD CROSS-REPO SETTINGS DO NOT EDIT --- //

Sources/SWIM/SWIMInstance.swift

@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 import ClusterMembership
+import CoreMetrics
 import Logging
 
 import struct Dispatch.DispatchTime

Sources/SWIMNIOExample/SWIMNIOHandler.swift

@@ -13,13 +13,20 @@
 //===----------------------------------------------------------------------===//
 
 import ClusterMembership
+import CoreMetrics
 import Logging
 import NIO
 import NIOFoundationCompat
 import SWIM
 
 import struct Dispatch.DispatchTime
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 /// `ChannelDuplexHandler` responsible for encoding/decoding SWIM messages to/from the `SWIMNIOShell`.
 ///
 /// It is designed to work with `DatagramBootstrap`s, and the contained shell can send messages by writing `SWIMNIOSWIMNIOWriteCommand`

Sources/SWIMNIOExample/SWIMNIOShell.swift

@@ -14,6 +14,7 @@
 
 import ClusterMembership
 import Logging
+import Metrics
 import NIO
 import SWIM
 

Tests/SWIMNIOExampleTests/SWIMNIOClusteredTests.swift

@@ -16,6 +16,7 @@ import ClusterMembership
 import Logging
 import NIO
 import SWIM
+import SWIMTestKit
 import XCTest
 
 @testable import SWIMNIOExample