fix: add flag to avoid thread cleanup when updating channel state (#1702)

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- [ ] Code changes are tested

## Description of the changes, What, Why and How?

https://getstream.zendesk.com/agent/tickets/77916 

Bug report:
- In RN, sometimes existing messages from the thread are wiped out after
the app is moved from the background <-> foreground
- The customer says it happens for React, too, but there is no
additional information there
- What I found (couldn't reproduce, but there is a possible code path):
- RN fires a `queryChannels` and `reloadThread` calls independently from
each other on state recovery. If `queryChannels` finishes after
`reloadThread`, the thread clean up wipes out thread messages.
- Since SDKs don't rely on threads being cleaned up (they always call
`getReplies` when a thread is opened), we could remove the thread
cleanup code. The reason I didn't want to do that because I think it's
possible that integrators using client directly may do something like:
```
if (!channel.state.threads[message.id]) {
 // get replies only if the thread is not initialized
}
```
- So I introduced a flag in the client as a somewhat hacky workaround ->
since we're planning a state rewrite anyway, I didn't want to spend any
more time in this rabbithole
- For React: I couldn't reproduce, nor could I see a viable code path
for this: as far as I can tell in the React thread reload happens in
response to parent message reference changing, which ensures that thread
reload can happen only after `queryChannels` finishes. We can ask the
customer to open a separate ticket for React, if they still the issue
there.

## Changelog

-

Author: szuperaz

src/channel_state.ts

@@ -243,7 +243,12 @@ export class ChannelState {
             .state.updateUserReference(message.user, this._channel.cid);
         }
 
-        if (initializing && message.id && this.threads[message.id]) {
+        if (
+          initializing &&
+          message.id &&
+          this.threads[message.id] &&
+          !this._channel.getClient().preventThreadCleanup
+        ) {
           // If we are initializing the state of channel (e.g., in case of connection recovery),
           // then in that case we remove thread related to this message from threads object.
           // This way we can ensure that we don't have any stale data in thread object

src/client.ts

@@ -321,6 +321,11 @@ export class StreamChat {
    * manually calling queryChannels endpoint.
    */
   recoverStateOnReconnect?: boolean;
+  /**
+   * If true, we will not clean up threads when channel state is in initializing state.
+   * The main use case for SDKs who do independent state recovery for channels.
+   */
+  preventThreadCleanup = false;
   moderation: Moderation;
   mutedChannels: ChannelMute[];
   mutedUsers: Mute[];