feat: adds support for custom networks

[mikeshultz]

What I did

Adds support for custom networks.

Depends on https://github.com/ApeWorX/ape/pull/1852

How I did it

When available, it will read the necessary information from the relevant ecosystem or from configuration. Example configuration:

networks:
  custom:
    - name: customnetwork
      chain_id: 31337
      default_provider: geth

geth:
  ethereum:
    customnetwork:
      uri: http://localhost:8545

etherscan:
  ethereum:
    rate_limit: 15
    customnetwork:
      uri: https://custom.scan
      api_uri: https://api.custom.scan/api

How to verify it

Checklist

• [ ] Passes all linting checks (pre-commit and CI jobs)
• [ ] New test cases have been added and are passing
• [ ] Documentation has been updated
• [ ] PR title follows Conventional Commit standard (will be automatically included in the changelog)

[mikeshultz]

Tests failing because they depend on a pending Ape change in the above linked PR.

[mikeshultz]

Tests are now fully working

[mikeshultz]

@antazoey I can't merge this due to the failing commit message, can you?