v3: Add view controller instantiation

[initFabian]

How to Test:

Test .homeViewController

• go into AppDelegate.swift for the Cely Demo target
• set the following option:

.homeStoryboard: UIStoryboard(name: "Main", bundle: nil)

• run application
• VERIFY: deprecation warning appears with Fix button
• Replace option with:

.homeViewController: UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "SecondViewController")

• run application
• VERIFY: application builds
• put in the credentials:
  • username: asdf
  • password: asdf
• VERIFY: you are brought to the set view controller

Test .loginViewController

• set the following option:

.loginStoryboard: UIStoryboard(name: "TestStoryboard", bundle: nil)

• run application
• VERIFY: deprecation warning appears with Fix button
• Replace option with:

.loginStoryboard: UIStoryboard(name: "TestStoryboard", bundle: nil).instantiateInitialViewController()

• run application
• VERIFY: a different login view controller is displayed. the elements aren't connected to anything so the login feature wont work.

[initFabian]

@alextall - btw, this adds support for SwiftUI as well. Im doing some work in the documentation Repo to add it.

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
  if let windowScene = scene as? UIWindowScene {
      let window = UIWindow(windowScene: windowScene)
//        window.rootViewController = UIHostingController(rootView: ContentView())
      self.window = window
      window.makeKeyAndVisible()
      Cely.setup(with: window, forModel: User(), requiredProperties: [.token], withOptions: [
        .homeViewController: UIHostingController(rootView: HomeContentView()),
        .loginCompletionBlock: { (username: String, password: String) in
            if username == "asdf" && password == "asdf" {
                Cely.save(username, forKey: "username")
                Cely.save("FAKETOKEN:\(username)\(password)", forKey: "token", securely: true)
                Cely.changeStatus(to: .loggedIn)
            }
        }
      ])
  }
}

[initFabian]

After this PR we'll add swift-format 😑