Add prompt rewriting for multiple messages inReasoningAgent

[giorgossideris]

Why are these changes needed?

Related issue number

Closes #755

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• I've added tests (if relevant) corresponding to the changes introduced in this PR.
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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see 74 files with indirect coverage changes

[Hk669]

@giorgossideris hey, added a comment in the issue. can you please check and give us any suggestions on that? thanks.