[Messenger example] create new group

xx-messenger example

• Add groups list screen
• Add new group screen
• Implement creating new group

Examples/xx-messenger/Sources/NewGroupFeature/NewGroupComponent.swift

+import AppCore
 import ComposableArchitecture
+import Foundation
+import XXModels
 
 public struct NewGroupComponent: ReducerProtocol {
   public struct State: Equatable {
-    public init() {}
+    public init(
+      contacts: IdentifiedArrayOf<XXModels.Contact> = []
+    ) {
+      self.contacts = contacts
+    }
+
+    public var contacts: IdentifiedArrayOf<XXModels.Contact>
   }
 
   public enum Action: Equatable {
     case start
+    case didFetchContacts([XXModels.Contact])
     case didFinish
   }
 
   public init() {}
 
+  @Dependency(\.app.dbManager.getDB) var db: DBManagerGetDB
+  @Dependency(\.app.mainQueue) var mainQueue: AnySchedulerOf<DispatchQueue>
+  @Dependency(\.app.bgQueue) var bgQueue: AnySchedulerOf<DispatchQueue>
+
   public func reduce(into state: inout State, action: Action) -> EffectTask<Action> {
     switch action {
     case .start:
+      return Effect
+        .catching { try db() }
+        .flatMap { $0.fetchContactsPublisher(.init()) }
+        .assertNoFailure()
+        .map(Action.didFetchContacts)
+        .subscribe(on: bgQueue)
+        .receive(on: mainQueue)
+        .eraseToEffect()
+
+    case .didFetchContacts(let contacts):
+      state.contacts = IdentifiedArray(uniqueElements: contacts)
       return .none
 
     case .didFinish: