c_nonce and jwt proof

[peppelinux]

in the issuance flow we use c_nonce and jwt proof without a proper definition of them

for instance, the c_nonce is a String containing a nonce to be used when creating a proof of possession of the key proof (see Section 7.2). When received, the Wallet MUST use this nonce value for its subsequent requests until the Credential Issuer provides a fresh nonce.

we have a quick definition here https://github.com/italia/eudi-wallet-it-docs/blob/versione-corrente/docs/en/pid-eaa-issuance.rst#token-response

we could imrpove this by giving more impl guidance about how this nonce is produces and how it can be used/verified with the jwt proof

[peppelinux]

scope
why we use c_nonce and why in italy we bind dpop with jwt proof