Simplify `call` to use `runComputation`; drop other code.
The RPC/GraphQL `call` operation differs in many ways from regular transaction
calls. The following flags are set, to disable various steps in processing.
All four are true (disabling the corresponding step) for `call`:
- `noIntrinsic`: Don't charge intrinsic gas.
- `noAccessList`: Don't initialise EIP2929 access list.
- `noGasCharge`: Don't charge sender account for gas.
- `noRefund`: Don't apply gas refund/burn rule.
Interestingly, the RPC/GraphQL `estimateGas` operation doesn't behave so
differently from regular transactions. It might be that not all these steps
should be disabled for `call` either. But until we investigate what
RPC/GraphQL clients are expecting, keep the same behaviour as before.
Signed-off-by: Jamie Lokier <jamie@shareable.org>