Allow selection of verification material encoding (CLI)

[noandrea]

Allow specifying

• pubKeyHex
• pubKeyMultibase

publicKeyMultibase should be the more standard one but pubKeyHex is the one implemented in aries-framework-go and therefore the preferred one for integration purposes

[noandrea]

resolved via a change in the universal resolver: https://github.com/allinbits/cosmos-cash-resolver#hyperledger-aries-specific-endpoint