Add iOS launch screen and app icon assets

- Created new app icon images for various sizes and added them to the asset catalog.
- Added launch images for different resolutions (1x, 2x, 3x) in the asset catalog.
- Updated the LaunchScreen storyboard to use the new launch images.
- Created a README for the launch image assets directory.
- Updated Info.plist to reference the new launch storyboard.
- Added a bridging header for Swift compatibility.
- Created initial test file for Runner application.
- Initialized project structure with necessary files and configurations.

ios/RunnerTests/RunnerTests.swift

@@ -0,0 +1,12 @@
+import Flutter
+import UIKit
+import XCTest
+
+class RunnerTests: XCTestCase {
+
+  func testExample() {
+    // If you add code to the Runner application, consider adding tests here.
+    // See https://developer.apple.com/documentation/xctest for more information about using XCTest.
+  }
+
+}