feat(gnarkd): added CancelProveJob and ListProveJob methods

[gbotrel]

// CancelProveJob does what it says it does.
rpc CancelProveJob(CancelProveJobRequest) returns (CancelProveJobResponse);

// ListProveJob does what it says it does.
rpc ListProveJob(ListProveJobRequest) returns (ListProveJobResponse);

additionally, a CreateProveJobRequest now has an optional TTL parameter (in seconds):

message CreateProveJobRequest {
	string circuitID = 1;
	optional int64 TTL = 2; // in seconds
}

cc @AlexandreBelling