Create Hello world for macOS (#1)

components/root/mac/view/RootView.swift

@@ -0,0 +1,24 @@
+import SwiftUI
+
+struct RootView: View {
+    @ObservedObject var vm: RootVM
+
+    init(_ vm: RootVM) {
+        self.vm = vm
+    }
+
+    var body: some View {
+        VStack(spacing: 16) {
+            Text("Hello, World!")
+                .font(.largeTitle)
+
+            Text(vm.countText)
+                .font(.title3.monospacedDigit())
+
+            Button("Increment") {
+                rootSet(F.didClickIncrement, true)
+            }
+        }
+        .padding(40)
+    }
+}