[TASK] Add support for multi-provider for EVM networks

[shekohex]

Overview

Relayers right now for each chain they relay on a single RPC, Relayers should make use of many of them so we improve the reliablity.

Checklist

• [ ] Allow the configurations for RPC endpoints to be either one endpoint or a list of endpoints
• [ ] Relayers should make use of all endpoints by either testing them first and then in a round-robin fashion.
• [ ] Add tests (which includes bad endpoints for testing)
• [ ] Update docs
• [ ] Update config files