Add a backup reporter

[akremstudy]

Summary

The purpose is for saving gas by avoiding reporting unnecessarily (when feed isn't used for example or only when data is needed).

• Adding a backup reporter that reports when certain conditions are met (for liquity or liquity forks that use chainlink as main feed)
• Can report using command telliot liquity -a my-account (see telliot reporter) with optional flag -clf to input feed address for queries other than eth-usd on mainnet and polygon. Conditions:
• main feed price stale (default set to 3600, could be set by using flag --frozen-timeout)
• large deviation between previous and latest (default set to 0.5, could be set by using flag --price-deviation)
• or if feed returns 0 values
• Also, note that tellor data is checked to see if its also stale.

  Steps Taken to QA Changes

• Adding tests for the backup reporter

Checklist

This pull request is:

• [ ] A documentation error, docs update, or typographical error fix
  • No tests or issue needed
• [ ] A code fix
  • Please reference the related issue by including "Closes <link to issue>" in this Pull Request's summary section.
    • If no issue exists, please create a bug report issue
  • Please include tests. Fixes without tests will not be accepted unless it's related to the documentation only.
  • Please make sure docs are updated if need be
• [x] A feature implementation
  • Please reference the related issue by including "Closes <link to issue>" in this Pull Request's summary section.
    • If no issue exists, please create a feature enhancement issue
  • Please include tests
  • Please make sure docs updates are both thorough and easy to reproduce by somebody with limited knowledge of the feature that you are submitting

Happy engineering!