api [nfc]: Rename StreamEvent to ChannelEvent

Fixes parts of zulip#631

Author: Khader-1

lib/api/model/events.dart

@@ -332,19 +332,19 @@ class RealmUserUpdateEvent extends RealmUserEvent {
 ///
 /// The corresponding API docs are in several places for
 /// different values of `op`; see subclasses.
-sealed class StreamEvent extends Event {
+sealed class ChannelEvent extends Event {
   @override
   @JsonKey(includeToJson: true)
   String get type => 'stream';
 
   String get op;
 
-  StreamEvent({required super.id});
+  ChannelEvent({required super.id});
 }
 
-/// A [StreamEvent] with op `create`: https://zulip.com/api/get-events#stream-create
+/// A [ChannelEvent] with op `create`: https://zulip.com/api/get-events#stream-create
 @JsonSerializable(fieldRename: FieldRename.snake)
-class StreamCreateEvent extends StreamEvent {
+class StreamCreateEvent extends ChannelEvent {
   @override
   String get op => 'create';
 
@@ -359,9 +359,9 @@ class StreamCreateEvent extends StreamEvent {
   Map<String, dynamic> toJson() => _$StreamCreateEventToJson(this);
 }
 
-/// A [StreamEvent] with op `delete`: https://zulip.com/api/get-events#stream-delete
+/// A [ChannelEvent] with op `delete`: https://zulip.com/api/get-events#stream-delete
 @JsonSerializable(fieldRename: FieldRename.snake)
-class StreamDeleteEvent extends StreamEvent {
+class StreamDeleteEvent extends ChannelEvent {
   @override
   String get op => 'delete';
 
@@ -376,7 +376,7 @@ class StreamDeleteEvent extends StreamEvent {
   Map<String, dynamic> toJson() => _$StreamDeleteEventToJson(this);
 }
 
-// TODO(#182) StreamUpdateEvent, for a [StreamEvent] with op `update`:
+// TODO(#182) StreamUpdateEvent, for a [ChannelEvent] with op `update`:
 //   https://zulip.com/api/get-events#stream-update
 
 /// A Zulip event of type `subscription`.

lib/model/channel.dart

@@ -129,7 +129,7 @@ class ChannelStoreImpl with ChannelStore {
     return false;
   }
 
-  void handleStreamEvent(StreamEvent event) {
+  void handleChannelEvent(ChannelEvent event) {
     switch (event) {
       case StreamCreateEvent():
         assert(event.streams.every((stream) =>

lib/model/store.dart

@@ -477,9 +477,9 @@ class PerAccountStore extends ChangeNotifier with ChannelStore, MessageStore {
         autocompleteViewManager.handleRealmUserUpdateEvent(event);
         notifyListeners();
 
-      case StreamEvent():
+      case ChannelEvent():
         assert(debugLog("server event: stream/${event.op}"));
-        _channels.handleStreamEvent(event);
+        _channels.handleChannelEvent(event);
         notifyListeners();
 
       case SubscriptionEvent():