Prevent duplicate GetOrCreateChannel calls when paginating messages

[VelikovPetar]

🎯 Goal

Resolves two issues which can result in multiple unnecessary calls to GetOrCreateChannel when paginating messages in a channel:

1. Don't call loadOlderMessages if MessageListController is already loading older messages
2. Don't call fillTheGap if ChannelLogic is loading older/newer messages. In this case, there will be no gap to be filled, so any calls to it are redundant.

🛠 Implementation details

1. Add guard for loadingOlderMessages in MessageListController.loadOlderMessages
2. Call ChannelLogic.fillTheGap ONLY when loading messages around ID (isFilteringAroundIdMessages)

🎨 UI Changes

NA

🧪 Testing

1. Open a channel
2. Scroll backwards (to load older messages)
3. Each page load should trigger ONLY 1 GetOrCreateChannel call (POST https://chat.stream-io-api.com/channels/<channelType>/<channelId>/query)
4. Observe the logs for no duplicate calls when paginating

[github-actions]

SDK Size Comparison 📏

SDK	Before	After	Difference	Status
stream-chat-android-client	5.25 MB	5.25 MB	0.00 MB	🟢
stream-chat-android-offline	5.48 MB	5.48 MB	0.00 MB	🟢
stream-chat-android-ui-components	10.59 MB	10.59 MB	0.00 MB	🟢
stream-chat-android-compose	12.81 MB	12.81 MB	0.00 MB	🟢

[sonarqubecloud]

Quality Gate failed

Failed conditions
6.9% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud