feat(llc): add AI events

[xsahil03x]

This pull request includes several changes to enhance the functionality and error handling of the stream_chat package. The most important changes include adding support for AI assistant states and events, improving error handling with stack traces, and updating various methods and classes to accommodate these new features.

AI Assistant Integration:

• Added support for AI assistant states and events in CHANGELOG.md.
• Introduced new AI-related fields (aiState, aiMessage, messageId) to the Event class and updated the serialization methods accordingly. [1] [2] [3] [4] [5]
• Added new AI-related event types (aiIndicatorUpdate, aiIndicatorStop, aiIndicatorClear) to EventType.

Error Handling Improvements:

• Enhanced StreamChatNetworkError to include an optional stack trace, improving error diagnostics. [1] [2] [3] [4] [5]
• Updated AuthInterceptor and StreamChatDioError to capture and pass stack traces. [1] [2]

Method and Class Updates:

• Added stopAIResponse method to the Channel class to handle stopping AI response generation.
• Improved ChannelClientState to handle watchers and members more efficiently. [1] [2] [3] [4]

Test Enhancements:

• Added tests for the new stopAIResponse method and AI-related fields in the Event class. [1] [2] [3] [4]

These changes collectively enhance the functionality, error handling, and test coverage of the stream_chat package.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 7 lines in your changes missing coverage. Please review.

Project coverage is 60.30%. Comparing base (4b062b2) to head (5e7d3e6).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
packages/stream_chat/lib/src/client/channel.dart	37.50%	5 Missing ⚠️
...eam_chat/lib/src/core/error/stream_chat_error.dart	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2057      +/-   ##
==========================================
+ Coverage   60.29%   60.30%   +0.01%     
==========================================
  Files         318      318              
  Lines       18580    18586       +6     
==========================================
+ Hits        11202    11209       +7     
+ Misses       7378     7377       -1     

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