feat: add tc recommendations to EXHORT

[zvigrinberg]

Integrate Trusted content recommendations into EXHORT' response payload.

1. Enrich response payload with Trusted Content recommendations fetched from TC Service' /recommend endpoint
2. For each dependency' purl, if recommendation exists, add the corresponding recommendation purl.
3. If recommendations are not found, then response body of exhort should remain the same without changes.

Remark: TC service' endpoint - /recommend is under ongoing development, so integration changes caused by it might follow.

[ruromero]

Thanks for the PR @zvigrinberg I have added some suggestions although the functionality doesn't change, it aligns with the existing code

[ruromero]

I have one concern about the overall approach. Wouldn't it be simpler to call the trustedContent before the providers and then keep the response in the exchange so that in the response handling we can have a common code to aggregate individually not only for recommendations but also for remediations as there will be where we have the CVEs information.

[zvigrinberg]

I have one concern about the overall approach. Wouldn't it be simpler to call the trustedContent before the providers and then keep the response in the exchange so that in the response handling we can have a common code to aggregate individually not only for recommendations but also for remediations as there will be where we have the CVEs information.

Let's discuss it tomorrow.

[zvigrinberg]

@ruromero As discussed, all the changes that you've requested are here, Please review and approve.