Created the API library in the Libraries package.

Libraries/Package.swift

@@ -11,15 +11,27 @@ let package = Package(
         .library(
             name: .Product.name.kit,
             targets: [
+                .Target.api,
                 .Target.foundation
             ]
         ),
     ],
     targets: [
+        .target(
+            name: .Target.api,
+            path: "API/Kit"
+        ),
         .target(
             name: .Target.foundation,
             path: "Foundation/Kit"
         ),
+        .testTarget(
+            name: .Target.api.test,
+            dependencies: [
+                .byName(name: .Target.api)
+            ],
+            path: "API/Test"
+        ),
         .testTarget(
             name: .Target.foundation.test,
             dependencies: [
@@ -41,6 +53,7 @@ private extension String {
     }
     
     enum Target {
+        static let api = "\(String.Product.name)API"
         static let foundation = "\(String.Product.name)Foundation"
     }
 }