spike: claims extraction during dsp comunication

[wolf4ood]

Feature Request

In some scenario it might be necessary to store the claims extracted from the counter party participant agent during DSP communication.

For example when negotiating a contract it might be useful to store in the contract agreement the claims at the time of the agreement reached.

Another example in the transfer process when communicating with a dataplane using the DPS (dataplane signaling) it might be useful to be able to forward claims extracted in order to allow the dataplane to apply fine grained access control if needed

We should try to reuse the policy engine to allow users to plug their own extraction strategy.

Which Areas Would Be Affected?

e.g., DPF, CI, build, transfer, etc.

Why Is the Feature Desired?

Are there any requirements?

Who will sponsor this feature?

Please @-mention the committer that will sponsor your feature.

Solution Proposal

If possible, provide a (brief!) solution proposal.

[ndr-brt]

This issue will be preceded by #5621 and #5622 and the scope will be about understanding where and how apply an eventual mapping to the claims before sending them to the data-plane