Fix manual string query

[akremstudy]

Summary

close #750
Added sub class for StringQuery ValueType to use the new method for encoding/decoding available in the current version of eth_abi.

Steps Taken to QA Changes

Added test using a good response value from here to check encoding/decoding.

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
• 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!

[0xSpuddy]

@tkernell can you please verify that this looks good for decoding in solidity? if so, we can merge and close imo. https://mumbai.polygonscan.com/tx/0xdc8f3491948800ce41c91c54bd0afa44826db77ae52c196f527f26ab25356c99

[tkernell]

looks good!