Update issue end point to support selective disclosure mandatory option

[Wind4Greg]

There are currently two VC specifications in process that support selective disclosure: Data Integrity ECDSA Cryptosuites v1.0 and BBS Cryptosuite v2023. The issue endpoint supports the credential and options properties.

As part of an issuer creating a "base proof" it is required that an array (possibly empty) of mandatoryPointers be input (see https://w3c.github.io/vc-di-ecdsa/#base-proof-transformation-ecdsa-sd-2023) to specify which statements must be disclosed by a holder when creating a derived credential.

Specifying the mandatoryPointers can be done via configuration, but it is also be desirable as an optional input as a field of the options property.