Update RFC001 and RFC002 to support x5c

[lalc]

For example, is the Appendix incomplete? https://github.com/EWC-consortium/eudi-wallet-rfcs/blob/main/ewc-rfc001-issue-verifiable-credential.md#appendix-a-public-key-resolution

Where should this info be captured? https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0-ID1.html#section-7.2.1.1

• kid: OPTIONAL. JOSE Header containing the key ID. If the Credential shall be bound to a DID, the kid refers to a DID URL which identifies a particular key in the DID Document that the Credential shall be bound to. It MUST NOT be present if jwk is present.
• jwk: OPTIONAL. JOSE Header containing the key material the new Credential shall be bound to. It MUST NOT be present if kid is present.
• x5c: OPTIONAL. JOSE Header containing a certificate or certificate chain corresponding to the key used to sign the JWT. This element MAY be used to convey a key attestation. In such a case, the actual key certificate will contain attributes related to the key properties.