Add support for BLS public keys in verification methods

[noandrea]

At the moment the DID module does not allow the addition of BLS curves keys to the verification methods of a DID.

Change it so that it is possible to add such keys, the verification methods types are:

• https://github.com/elesto-dao/elesto/blob/c856306d57f34f2b380dc79434c2e3b582769181/x/did/did_verification_material.go#L28
• https://github.com/elesto-dao/elesto/blob/c856306d57f34f2b380dc79434c2e3b582769181/x/did/did_verification_material.go#L29

[github-actions[bot]]

This issue was marked as stale because there was no activity for 15 days

[github-actions[bot]]

This issue was marked as stale because there was no activity for 15 days

[github-actions[bot]]

This issue was marked as stale because there was no activity for 15 days