feat: add support for multiple signing algorithms

[nanderstabel]

Description of change

Previously all data in all flows where signed using EdDSA by default. This current PR adds support for the configuration of multiple singing algorithms.

Links to any relevant issues

Closes #71

How the change has been tested

Adjusted relevant tests. The changes made in this PR have also been tested through:

• UniMe: https://github.com/impierce/identity-wallet/pull/236
• UniCore: https://github.com/impierce/ssi-agent/pull/57
• did-manager: https://github.com/impierce/did-manager/pull/18

Definition of Done checklist

Add an x to the boxes that are relevant to your changes.

• [x] I have followed the contribution guidelines for this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes