Update example app

This MR updates the example app so it uses the new Bindings wrapper.

• Present landing page with options to create or load cMix.
• Allow removing cMix if stored.
• Start/stop network follower.
• Show network follower status.
• Observe and display network health status.

Example/example-app/Sources/MyContactFeature/MyContactFeature.swift

-import Combine
-import ComposableArchitecture
-import ComposablePresentation
-import ElixxirDAppsSDK
-import ErrorFeature
-
-public struct MyContactState: Equatable {
-  public init(
-    id: UUID,
-    contact: Data? = nil,
-    isMakingContact: Bool = false,
-    error: ErrorState? = nil
-  ) {
-    self.id = id
-    self.contact = contact
-    self.isMakingContact = isMakingContact
-    self.error = error
-  }
-
-  public var id: UUID
-  public var contact: Data?
-  public var isMakingContact: Bool
-  public var error: ErrorState?
-}
-
-public enum MyContactAction: Equatable {
-  case viewDidLoad
-  case observeMyContact
-  case didUpdateMyContact(Data?)
-  case makeContact
-  case didFinishMakingContact(NSError?)
-  case didDismissError
-  case error(ErrorAction)
-}
-
-public struct MyContactEnvironment {
-  public init(
-    getClient: @escaping () -> Client?,
-    getIdentity: @escaping () -> Identity?,
-    observeContact: @escaping () -> AnyPublisher<Data?, Never>,
-    updateContact: @escaping (Data?) -> Void,
-    bgScheduler: AnySchedulerOf<DispatchQueue>,
-    mainScheduler: AnySchedulerOf<DispatchQueue>,
-    error: ErrorEnvironment
-  ) {
-    self.getClient = getClient
-    self.getIdentity = getIdentity
-    self.observeContact = observeContact
-    self.updateContact = updateContact
-    self.bgScheduler = bgScheduler
-    self.mainScheduler = mainScheduler
-    self.error = error
-  }
-
-  public var getClient: () -> Client?
-  public var getIdentity: () -> Identity?
-  public var observeContact: () -> AnyPublisher<Data?, Never>
-  public var updateContact: (Data?) -> Void
-  public var bgScheduler: AnySchedulerOf<DispatchQueue>
-  public var mainScheduler: AnySchedulerOf<DispatchQueue>
-  public var error: ErrorEnvironment
-}
-
-public let myContactReducer = Reducer<MyContactState, MyContactAction, MyContactEnvironment>
-{ state, action, env in
-  switch action {
-  case .viewDidLoad:
-    return .merge([
-      .init(value: .observeMyContact),
-    ])
-
-  case .observeMyContact:
-    struct EffectId: Hashable {
-      let id: UUID
-    }
-    return env.observeContact()
-      .removeDuplicates()
-      .map(MyContactAction.didUpdateMyContact)
-      .subscribe(on: env.bgScheduler)
-      .receive(on: env.mainScheduler)
-      .eraseToEffect()
-      .cancellable(id: EffectId(id: state.id), cancelInFlight: true)
-
-  case .didUpdateMyContact(let contact):
-    state.contact = contact
-    return .none
-
-  case .makeContact:
-    state.isMakingContact = true
-    return Effect.future { fulfill in
-      guard let identity = env.getIdentity() else {
-        fulfill(.success(.didFinishMakingContact(NoIdentityError() as NSError)))
-        return
-      }
-      do {
-        env.updateContact(try env.getClient()?.makeContactFromIdentity(identity: identity))
-        fulfill(.success(.didFinishMakingContact(nil)))
-      } catch {
-        fulfill(.success(.didFinishMakingContact(error as NSError)))
-      }
-    }
-    .subscribe(on: env.bgScheduler)
-    .receive(on: env.mainScheduler)
-    .eraseToEffect()
-
-  case .didFinishMakingContact(let error):
-    state.isMakingContact = false
-    if let error = error {
-      state.error = ErrorState(error: error)
-    }
-    return .none
-
-  case .didDismissError:
-    state.error = nil
-    return .none
-
-  case .error(_):
-    return .none
-  }
-}
-
-public struct NoIdentityError: Error, LocalizedError {
-  public init() {}
-}
-
-#if DEBUG
-extension MyContactEnvironment {
-  public static let failing = MyContactEnvironment(
-    getClient: { fatalError() },
-    getIdentity: { fatalError() },
-    observeContact: { fatalError() },
-    updateContact: { _ in fatalError() },
-    bgScheduler: .failing,
-    mainScheduler: .failing,
-    error: .failing
-  )
-}
-#endif