[Task] Add support for VC Data Model 2.0

[eike-hass]

Description

Add support for the upcoming VC Data Model v2.0 in a way that allows multiple data models to coexist.

Motivation

Stay compatible with the latest recommendations in the identity ecosystem and create the capabilities needed to support multiple models/encodings in parallel.

Resources

https://www.w3.org/TR/vc-data-model-2.0/

To-do list

Create a task-specific to-do list. Please link PRs that match the TODO list item behind the item after it has been submitted.

• [ ] Multi Model Design
• [ ] Rust implementation
• [ ] Wasm implementation

Change checklist

Add an x to the boxes that are relevant to your changes, and delete any items that are not.

• [ ] The feature or fix is implemented in Rust and across all bindings whereas possible.
• [ ] The feature or fix has sufficient testing coverage
• [ ] All tests and examples build and run locally as expected
• [ ] Every piece of code has been document according to the documentation guidelines.
• [ ] If conceptual documentation (mdbook) and examples highlighting the feature exist, they are properly updated.
• [ ] If the feature is not currently documented, a documentation task Issue has been opened to address this.

### Tasks
- [ ] https://github.com/iotaledger/identity.rs/issues/1294
- [ ] https://github.com/iotaledger/identity.rs/issues/1307
- [ ] Actually implement VC Data Model 2.0
- [ ] Fully integrate new structure in library
- [ ] Demo internal proof using `DataIntegerityProof``, potentially using `eddsa-jcs-2022`