Add Currency in Ledger CLI doesn't connect with credentials

[darcys22]

Still uses only the insecure method to connect.

When we upgraded the connection methods for GRPC new logic was added to the code to include a check for flags, read the certificate files and then connect using the secure method. Else connect to the GRPC server using the insecure method.

This can be seen in the code within ledger_cli/transaction.go in the “send” function for example.

However in ledger_cli/addcurrency.go the only option is to connect using the insecure method

conn, err := grpc.Dial(address, grpc.WithInsecure())

This section of the code needs to be updated to be in line with the rest of the codebase and allow for secure connections.