Add further relay chain configuration

[iamacook]

Summary

We currently support relaying on Gnosis Chain, Arbitrum and Sepolia. This adds further configuration for: Optimism, BNB, Polygon, Polygon zkEVM, Base, Avalanche, Linea and Blast.

Changes

• Add env. var. configuration for aforementioned chains to:
  • .env.sample
  • docker-compose.yaml
  • (Test) configuration
  • Confirguration validator
    • Test coverage