api [nfc]: Rename references of ChannelPostPolicy to match new name

Author: Khader-1

lib/api/model/model.dart

@@ -320,9 +320,9 @@ class ZulipStream {
   final bool isWebPublic; // present since 2.1, according to /api/changelog
   final bool historyPublicToSubscribers;
   final int? messageRetentionDays;
-
-  final ChannelPostPolicy streamPostPolicy;
-  // final bool isAnnouncementOnly; // deprecated for `streamPostPolicy`; ignore
+  @JsonKey(name: 'stream_post_policy')
+  final ChannelPostPolicy channelPostPolicy;
+  // final bool isAnnouncementOnly; // deprecated for `channelPostPolicy`; ignore
 
   // TODO(server-6): `canRemoveSubscribersGroupId` added in FL 142
   // TODO(server-8): in FL 197 renamed to `canRemoveSubscribersGroup`
@@ -348,7 +348,7 @@ class ZulipStream {
     required this.isWebPublic,
     required this.historyPublicToSubscribers,
     required this.messageRetentionDays,
-    required this.streamPostPolicy,
+    required this.channelPostPolicy,
     required this.canRemoveSubscribersGroup,
     required this.streamWeeklyTraffic,
   });
@@ -419,7 +419,7 @@ class Subscription extends ZulipStream {
     required super.isWebPublic,
     required super.historyPublicToSubscribers,
     required super.messageRetentionDays,
-    required super.streamPostPolicy,
+    required super.channelPostPolicy,
     required super.canRemoveSubscribersGroup,
     required super.streamWeeklyTraffic,
     required this.desktopNotifications,

lib/api/model/model.g.dart

@@ -171,7 +171,7 @@ ZulipStream stream({
   bool? isWebPublic,
   bool? historyPublicToSubscribers,
   int? messageRetentionDays,
-  ChannelPostPolicy? streamPostPolicy,
+  ChannelPostPolicy? channelPostPolicy,
   int? canRemoveSubscribersGroup,
   int? streamWeeklyTraffic,
 }) {
@@ -186,7 +186,7 @@ ZulipStream stream({
     isWebPublic: isWebPublic ?? false,
     historyPublicToSubscribers: historyPublicToSubscribers ?? true,
     messageRetentionDays: messageRetentionDays,
-    streamPostPolicy: streamPostPolicy ?? ChannelPostPolicy.any,
+    channelPostPolicy: channelPostPolicy ?? ChannelPostPolicy.any,
     canRemoveSubscribersGroup: canRemoveSubscribersGroup ?? 123,
     streamWeeklyTraffic: streamWeeklyTraffic,
   );
@@ -219,7 +219,7 @@ Subscription subscription(
     isWebPublic: stream.isWebPublic,
     historyPublicToSubscribers: stream.historyPublicToSubscribers,
     messageRetentionDays: stream.messageRetentionDays,
-    streamPostPolicy: stream.streamPostPolicy,
+    channelPostPolicy: stream.channelPostPolicy,
     canRemoveSubscribersGroup: stream.canRemoveSubscribersGroup,
     streamWeeklyTraffic: stream.streamWeeklyTraffic,
     desktopNotifications: desktopNotifications ?? false,