Change credentials create test vectors

[nitro-neal]

Currently the test vector uses .fromJson and only works in kotlin.

Need to change the test vector input so it's the input of VerifiableCredential.create() and works across all sdks

public fun <T> create(
  type: String,
  issuer: String,
  subject: String,
  data: T,
  credentialStatus: CredentialStatus? = null,
  issuanceDate: Date = Date(),
  expirationDate: Date? = null
): VerifiableCredential {

[nitro-neal]

#149

[decentralgabe]

related to #168