Improve error message while the operator doesn't have enough ether as gas fee for opt-in

[renlulu]

Right now, while a operator opt-in to our AVS contract, if there is a contract call revert, e.g. not whitelisted, the opt-in would fail with a concrete reason, however, if the opt-in fails due to gas fee issue, there is nothing but "exection reverted":

2024-05-20T20:08:43.412Z        INFO    operator/registration.go:78     RegisterOperatorInQuorumWithAVSRegistryCoordinator      {"quorumNumbers": 0, "socket": "", "operatorToAvsRegistrationSigExpiry": "1717235680"}
2024-05-20T20:08:43.412Z        INFO    avsregistry/writer.go:197       registering operator with the AVS's registry coordinator        {"avs-service-manager": "0xAE9a4497dee2540DaF489BeddB0706128a99ec63", "operator": "0xbE4B4Fa92b6767FDa2C8D1db53A286834dB19638", "quorumNumbers": "AA==", "socket": ""}
2024-05-20T20:08:43.955Z        ERROR   operator/registration.go:93     Unable to register operator with avs registry coordinator       {"error": "execution reverted"}
2024/05/20 20:08:43 execution reverted 

So, we need a grace solution to identify such case, and make the error message more readable and helpful.