fix: allow user to pass in a closure for custom action on email link and phone auth buttons

[russellwheatley]

• Email & phone auth buttons are different to the other providers as they push user to different Views but it is currently causing compiler error. This PR fixes this by removing @MainActor from closure parameters in withPhoneSignIn(onTap:) and withEmailSignIn(onTap:) methods because it prevented users from passing closures from non-@MainActor contexts (like init()), while still ensuring main actor execution happens internally where the closures are actually invoked in the UI layer.

So for default Views, it remains the same:

authService = AuthService(
      configuration: configuration
    )
    .withEmailSignIn()
    .withPhoneSignIn()

For custom action on button tap, do this:

authService = AuthService(
      configuration: configuration
    )
    .withEmailSignIn(){
		print("do something")
	}
    .withPhoneSignIn(){
		print("do something")
	}