[Add] Logging for each message of GPTAssistant

[krishnashed]

@IANTHEREAL @ekzhu

Why are these changes needed?

It solves the logging issue with GPTAssistant Sequential chats, where only the last message of a sequential step was being logged, rather than logging each GPTAssistant Agent interaction.

Related issue number

Closes #2644

Checks

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• [ ] I've added tests (if relevant) corresponding to the changes introduced in this PR.
• [ ] I've made sure all auto checks have passed.