[Reactions v2] Add `reactionGroups` to `ChatMessage`

[nuno-vieira]

🔗 Issue Links

Relates to https://github.com/GetStream/ios-issues-tracking/issues/787

🎯 Goal

Adds reactionsGroups to ChatMessage so that reactions can be sorted by date.

📝 Summary

• Adds reactionsGroups to ChatMessage so that reactions can be sorted by date.
• Adds firstReactionAt and lastReactionAt from reactionGroups in ChatMessageReactionData for Components.reactionsSorting
• Adds optimistic updates for the reactions group
• Fixes existing issues of optimistic updates
• Adds tests for optimistic updates
• Updates Slack example app to sort reactions in the message list by firstReactionAt

🛠 Implementation

Adds reactionsGroups to ChatMessage which includes the reactionCounts, reactionScores and also the dates for the first reaction and last reaction of the type. The reactionCounts and reactionScores are still kept for backwards compability.

🧪 Manual Testing Notes

1. Open Demo App
2. React to messages
3. The order of the reactions in the message list should be sorted by the date of the first reaction of that type and count (Like slack)

Note: Currently only working for new reactions.

☑️ Contributor Checklist

• [x] I have signed the Stream CLA (required)
• [x] This change follows zero ⚠️ policy (required)
• [x] This change should be manually QAed
• [x] Changelog is updated with client-facing changes
• [x] New code is covered by unit tests
• [ ] Comparison screenshots added for visual changes
• [ ] Affected documentation updated (docusaurus, tutorial, CMS)

[github-actions[bot]]

	1 Warning
:warning:	Big PR

Generated by :no_entry_sign: Danger

[martinmitrevski]

Btw, the slack app doesn't build, please check before merging

[sonarqubecloud[bot]]

Quality Gate passed

Issues
64 New issues
0 Accepted issues

Measures
0 Security Hotspots
83.1% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud