Create imported credential from hard-coded zkprogram metadata

[mitschabaude]

Currently, when creating an imported credential we need to compute featureFlags and maxProofsVerified by running all the methods. Later, also the verification key often needs to be created by calling compile(), because we want to hard-code it in our attestation spec.

For imported specs shipped with our library, we should create that data at build time and check that it didn't change in CI. So that users of the library have these specs available immediately without compiling.