Add credential schema

[nitro-neal]

Implement Credential Schema

A credential schema defines the structure and content of the data, enabling verifiers to assess if the data adheres to the established schema.

https://www.w3.org/TR/vc-data-model/#data-schemas

• Add CredentialSchema type
• Add optional field to VcCreateOptions
• Update KYC unit test to have latest kyc cred

[codecov-commenter]

Codecov Report

Merging #301 (ca0ef94) into main (bf27a24) will increase coverage by 0.04%. The diff coverage is 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #301 +/- ## ========================================== + Coverage 73.54% 73.58% +0.04% ========================================== Files 45 45 Lines 2158 2162 +4 Branches 401 402 +1 ========================================== + Hits 1587 1591 +4 Misses 376 376 Partials 195 195 ``` | [Components](https://app.codecov.io/gh/TBD54566975/web5-kt/pull/301/components?src=pr&el=components&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=TBD54566975) | Coverage Δ | | |---|---|---| | [credentials](https://app.codecov.io/gh/TBD54566975/web5-kt/pull/301/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=TBD54566975) | `81.27% <100.00%> (+0.14%)` | :arrow_up: | | [crypto](https://app.codecov.io/gh/TBD54566975/web5-kt/pull/301/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=TBD54566975) | `49.16% <ø> (ø)` | | | [dids](https://app.codecov.io/gh/TBD54566975/web5-kt/pull/301/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=TBD54566975) | `80.50% <ø> (ø)` | | | [common](https://app.codecov.io/gh/TBD54566975/web5-kt/pull/301/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=TBD54566975) | `65.21% <ø> (ø)` | |