chore: replace ursa lib with anoncreds-clsignatures-rs

[amanji]

Replaces ursa library with anoncreds-clsignatures-rs.
Removes some external dependencies which are now packaged with the updated library.
Resolves: #221
Resolves: #224

Many thanks to @andrewwhitehead for help on this.

[amanji]

Tagging @berendsliedrecht and @TimoGlastra for a review request.

[swcurran]

Note about this on the interface changes made to those using this library:

• The call to issue a credential no longer requires the tails file as a parameter.
• The call to revoke a credential no longer requires the tails file as a parameter, adds the CredDefinition and the revocation registry private key as parameters.

[genaris]

I think that the JS part is fine. It misses the updates for React Native wrapper though. Not a common use case of course (and not sure if current issuance/revocation methods are properly working as we didn't test them systematically), so won't consider it as a blocker if not added to this PR.

[amanji]

Yes I should have mentioned that the RN wrappers were not updated. I assume they could be updated in a follow up PR to this.

[andrewwhitehead]

anoncreds-clsignatures 0.2 is out now with a few more updates, but I can add another PR for that. I think the revocation status list creation could be optimized so I'll look at that at the same time.

[swcurran]

anoncreds-clsignatures 0.2 is out now with a few more updates, but I can add another PR for that. I think the revocation status list creation could be optimized so I'll look at that at the same time.

@andrewwhitehead — what is the action here? Can we merge this, do we need to update to 0.2? Your note implies that we can do the 0.2 update later, but then you didn’t approve this. Thanks!