Bitstring Status List should use VC DataModel 2.0

# Bug Report

## Describe the Bug

Currently, the Issuer-side implementation of the BitstringStatusList implicitly uses VC DataModel 1.1. THis is done by using `CredentialFormat.VC1_0_JWT` where actually `CredentialFormat.VC2_0_JOSE` should be used.

In addition, this requires enhancements to the credential generation. In particular this requires the implementation of a `EnvelopedJwtCredentialGenerator`, which produces VC DataModel 2.0 enveloped credentials.

### Expected Behavior

BitstringStatusList credentials use VC DataModel 2.0, JOSE (enveloped credentials)

### Observed Behavior

our BitStringStatusList credentials are conformant to VC DataModel 1.1, where they whould conform to 2.0

## Possible Implementation

_You already know the root cause of the erroneous state and how to fix it? Feel free to share your thoughts._