Enable MemberImportVisibility check on all targets

Author: rnro

Package.swift

@@ -117,3 +117,9 @@ let package = Package(
   dependencies: dependencies,
   targets: targets
 )
+
+for target in package.targets {
+  var settings = target.swiftSettings ?? []
+  settings.append(.enableUpcomingFeature("MemberImportVisibility"))
+  target.swiftSettings = settings
+}