api: Add realmWaitingPeriodThreshold to InitialSnapshot

This is necessary in the next commit(s) where wee need to determine if a
a user has become a full member.

For how to determine if a user is a full member, see:
  https://zulip.com/api/roles-and-permissions#determining-if-a-user-is-a-full-member

Author: sm-sayedi

lib/api/model/initial_snapshot.dart

@@ -64,6 +64,14 @@ class InitialSnapshot {
 
   final List<UserTopicItem>? userTopics; // TODO(server-6)
 
+  /// The number of days until a user's account is treated as a full member.
+  ///
+  /// Search for "realm_waiting_period_threshold" in https://zulip.com/api/register-queue.
+  /// 
+  /// For how to determine if a user is a full member, see:
+  ///   https://zulip.com/api/roles-and-permissions#determining-if-a-user-is-a-full-member
+  final int realmWaitingPeriodThreshold;
+
   final Map<String, RealmDefaultExternalAccount> realmDefaultExternalAccounts;
 
   final int maxFileUploadSizeMib;
@@ -115,6 +123,7 @@ class InitialSnapshot {
     required this.streams,
     required this.userSettings,
     required this.userTopics,
+    required this.realmWaitingPeriodThreshold,
     required this.realmDefaultExternalAccounts,
     required this.maxFileUploadSizeMib,
     required this.realmUsers,

lib/api/model/initial_snapshot.g.dart

@@ -713,6 +713,7 @@ InitialSnapshot initialSnapshot({
   List<ZulipStream>? streams,
   UserSettings? userSettings,
   List<UserTopicItem>? userTopics,
+  int? realmWaitingPeriodThreshold,
   Map<String, RealmDefaultExternalAccount>? realmDefaultExternalAccounts,
   int? maxFileUploadSizeMib,
   List<User>? realmUsers,
@@ -745,6 +746,7 @@ InitialSnapshot initialSnapshot({
       emojiset: Emojiset.google,
     ),
     userTopics: userTopics,
+    realmWaitingPeriodThreshold: realmWaitingPeriodThreshold ?? 0,
     realmDefaultExternalAccounts: realmDefaultExternalAccounts ?? {},
     maxFileUploadSizeMib: maxFileUploadSizeMib ?? 25,
     realmUsers: realmUsers ?? [],