Migrate to new Fabric Gateway client

[jt-nti]

It would be great to move from the current Go SDK to the new Fabric Gateway client when possible.

[nguyer]

@jt-nti If we swapped libraries would this break compatibility with Fabric 2.3? It seems like Fabric Gateway may only work with 2.4 and forward? https://github.com/hyperledger/fabric-gateway/blob/main/pkg/client/README.md#compatibility

[jt-nti]

Hi @nguyer, that's correct, it would only work with Fabric 2.4+ with peers that have the Gateway functionality enabled.

[torrespro]

See: hyperledger/firefly#1414 and hyperledger/firefly-cli#268

[johannww]

One reason for switching: ED25519 support

❯ curl -X GET "http://localhost:3000/blocks/1" 
-H "x-firefly-channel: mychannel" -H "x-firefly-signer: Admin"
{"error":"Failed to get channel client. failed to get client context to create channel client:
 getting private key from cert failed: fetching public key from cert failed: Failed to import 
certificate's public key: Failed importing key with opts [\u0026{true}]: Certificate's public 
key type not recognized. Supported keys: [ECDSA]"}%

[EnriqueL8]

Thanks @johannww - happy to accept a contribution here 😃