[3806] add Swift Package Manager support

Author: carlosmejiagrove

Package.swift

@@ -0,0 +1,26 @@
+// swift-tools-version:5.7
+import PackageDescription
+
+let package = Package(
+    name: "AXStateButton",
+    platforms: [
+        .iOS(.v14)
+    ],
+    products: [
+        .library(
+            name: "AXStateButton",
+            targets: ["AXStateButton"])
+    ],
+    dependencies: [],
+    targets: [
+        .target(
+            name: "AXStateButton",
+            dependencies: [],
+            path: "Source",
+            publicHeadersPath: "include",
+            cSettings: [
+                .headerSearchPath("."),
+            ]
+        )
+    ]
+)