CLI support for mainnet and other improvements

[cuongdo]

Checklist:

• [x] Code contains relevant tests for the problem you are solving
• [x] Ensure all new and existing tests pass
• [x] Update any relevant READMEs and docs

Description:

• Add support for mainnet
• Reduced verbosity of retry logging
• Cleaned up withRetries interface
• Improved some error messages

Together, these changes give me more confidence that the CLI will work with the testnets and mainnet. I tested the CLI with ganache-cli, Rinkeby, and (in a very limited way) mainnet.