Pass cached tokens to RequestUsage

[sukeesh]

Why are these changes needed?

Related issue number

Closes #7111

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://github.com/microsoft/autogen/blob/main/CONTRIBUTING.md to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[priteesshhh]

I analyzed this issue but couldn't identify the affected files. Could you please provide more details about which files need to be modified?

[sukeesh]

I analyzed this issue but couldn't identify the affected files. Could you please provide more details about which files need to be modified?

@priteesshhh I have already modified the files that I am supposed to modify. I am not sure what you mean.

[putrasurya]

I analyzed this issue but couldn't identify the affected files. Could you please provide more details about which files need to be modified?

@priteesshhh I have already modified the files that I am supposed to modify. I am not sure what you mean.

@sukeesh He throws the same comment on all PRs. Looks like he's a bot.

[priteesshhh]

I analyzed this issue but couldn't identify the affected files. Could you please provide more details about which files need to be modified?

@priteesshhh I have already modified the files that I am supposed to modify. I am not sure what you mean.

@sukeesh He throws the same comment on all PRs. Looks like he's a bot.

Hey @sukeesh and @putrasurya, apologies for the confusion earlier — I was running an automated bot that analyzes issues and suggests potential fixes. The comment about “identifying affected files” was generated by that script, not a manual review. Sorry for the noise and misunderstanding. Please ignore that message. Thanks for your patience! 🙏

[sukeesh]

@microsoft-github-policy-service agree

[sukeesh]

@victordibia @ekzhu Please review.