Add batch event process for substrate

[freddyli7]

Since relayer now supports batch event process for EVM, it should also support it for substrate

Implementation details

details could be found in the SoW research doc

Testing details

Unit test
E2E test that with local substrate evm with manually sending token transfer extrinsic

Acceptance Criteria

Relayer should be able to batch substrate events
Batch event number or block number should be configurable