This is a huge PR. A few things got clumped together as I found and sorted out issues.
I am able to break this down if you prefer. Just let me know!

resolves #174

Breaking Changes

jwt::picojson_traits became jwt::traits::kazuho_picojson

All traits are within a namespace and follow the convention of author_project

Highlists

• coverage for all JSON libraries
  • tests
  • examples
  • badging
  • refactored actions installing them
• automatic code generation for tests and default traits
  • some exceptions apply
• linting now checks all files
  • new actions + refactored workflows

Files to skip

• tests/traits/** are all auto generated
• examples/** auto generated or moved
• jwt/traits/*/defaults.h auto generated