Add CreateUserFriendlyErrorMessage functor

Sources/ElixxirDAppsSDK/Functors/CreateUserFriendlyErrorMessage.swift

+import Bindings
+import XCTestDynamicOverlay
+
+public struct CreateUserFriendlyErrorMessage {
+  public var run: (String) -> String
+
+  public func callAsFunction(_ errorString: String) -> String {
+    run(errorString)
+  }
+}
+
+extension CreateUserFriendlyErrorMessage {
+  public static let live = CreateUserFriendlyErrorMessage { errorString in
+    BindingsCreateUserFriendlyErrorMessage(errorString)
+  }
+}
+
+extension CreateUserFriendlyErrorMessage {
+  public static let unimplemented = CreateUserFriendlyErrorMessage(
+    run: XCTUnimplemented("\(Self.self)")
+  )
+}