fix(RelayFeeCalculator): Return maxFeePerGas rather than tokenGasCost…

… / nativeGasCost

If we divide `tokenGasCost / nativeGasCost` then we'll get the L1GasCost + L2GasPrice components for the gas price for OpStack, because OpStack adds this L1GasCost component to the full total gas cost.

The SDK should return the `gasPrice = baseFee + priorityFee` to help with debugging against the API, for example against this PR across-protocol/frontend#1335

src/relayFeeCalculator/chain-queries/baseQuery.ts

@@ -155,7 +155,7 @@ export class QueryBase implements QueryInterface {
     return {
       nativeGasCost, // Units: gas
       tokenGasCost, // Units: wei (nativeGasCost * wei/gas)
-      gasPrice: tokenGasCost.div(nativeGasCost), // Units: wei/gas
+      gasPrice: BigNumber.from(gasPrice.toString()), // Units: wei/gas, does not include l1GasCost for OP stack chains
     };
   }