Epic: create and join rooms - Start Chat (#680)

* add start chat flow with UI

* add feature flag for start chat

* add changelog

* fix naming and tests

* fix empty display name in user cell

* Update ElementX/Sources/Application/AppSettings.swift

Co-authored-by: Alfonso Grillo <alfogrillo@element.io>

* add screenshots from UI test

* fix swiftFormat and add identifiers

* fix warnings

---------

Co-authored-by: Alfonso Grillo <alfogrillo@element.io>

ElementX/Sources/Screens/HomeScreen/HomeScreenCoordinator.swift

@@ -29,6 +29,7 @@ enum HomeScreenCoordinatorAction {
     case presentSettingsScreen
     case presentFeedbackScreen
     case presentSessionVerificationScreen
+    case presentStartChatScreen
     case signOut
 }
 
@@ -62,6 +63,8 @@ final class HomeScreenCoordinator: CoordinatorProtocol {
                 self.callback?(.presentSessionVerificationScreen)
             case .signOut:
                 self.callback?(.signOut)
+            case .presentStartChatScreen:
+                self.callback?(.presentStartChatScreen)
             }
         }
     }