Add new simple examples for Sepolia testnet

[jasonthewhale]

Since Goerli gonna sunset, it makes sense to add new example based on Sepolia testnet.

Changes:

• Seems simulation only works on mainnet, so ignore simulation when "USE_GOERLI" is "True";
• Replace Goerli setup with Sepolia in "simple_new.py";
• Provide popular bundle builders that compatible with "eth_sendBundle" method.