Can't sign transactions on testnet

[ezra-sg]

Overview

The recent changes to add graymass fuel don't currently account for non-fuel-enabled chains such as testnet. The following error occurs if you attempt to sign a transaction, such as Add CPU

Acceptance criteria

• the usage of graymass fuel should be dependent on a per-chain configuration. if a chain does not support fuel or is configured to not use fuel, no fuel wrapper should be added to the tx