Add AppVersionText view

Examples/xx-messenger/Sources/AppCore/SharedUI/AppVersionText.swift

+import SwiftUI
+
+public struct AppVersionText: View {
+  public init() {}
+
+  public var body: some View {
+    Text("v\(version) (\(build))")
+  }
+
+  var version: String = Bundle.main.shortVersionString ?? "0.0.0"
+  var build: String = Bundle.main.versionString ?? "0"
+}
+
+private extension Bundle {
+  var shortVersionString: String? {
+    infoDictionary?["CFBundleShortVersionString"] as? String
+  }
+  var versionString: String? {
+    infoDictionary?["CFBundleVersion"] as? String
+  }
+}
+
+#if DEBUG
+struct AppVersionText_Previews: PreviewProvider {
+  static var previews: some View {
+    AppVersionText()
+      .padding()
+      .previewLayout(.sizeThatFits)
+  }
+}
+#endif