suggestion:replace hardcode "bridge service" with B_BRIDGE

[ddl-hust]

Describe the feature request

Read this document to learn more about how taiko deal with bridge, found some issues:

1. isSignalReceived in doc cannot found, _isSignalReceived is private method. so original isSignalReceived seems renamed to isMessageReceived

2. follow _isSignalReceived,trigger a internal contract call verifySignalReceived

   {
       try ISignalService(_signalService).verifySignalReceived(
           _chainId, resolve(_chainId, "bridge", false), _signal, _proof
       ) {
           return true;
       } catch {
           return false;
       }
   }

   resolve use chainID resolve name-to-address, LibString.sol define mappings between bytes32("bridge") and B_BRIDGE, My suggestion is to use unified identifiers globally to avoid hard coding and reduce errors.

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