Inconsistent use of `format` in CIP

[arnoweiss]

What's wrong?

The CredentialRequestMessage and CredentialContainer each contain info on credentialType and format.

1. The CredentialContainer does not have a textual description on the format property.
2. CredentialRequestMessage has jwt/ld and vcdm in the example. CredentialContainer only has json-ld/jwt

Why is this a bug?

We should clearly state that the format property is the same in both messages.

How could it be fixed?

Both 1. and 2. can be fixed by harmonizing the description and examples.

More context

No response

[jimmarino]

Document the difference between format and profile.

Define format strings.