Migrate JSON tests from hed-specification to hed-tests

The JSON tests, which have been previously housed in [hed-standard/hed-specification](https://github.com/hed-standard/hed-specification) are now housed in  [hed-standard/hed-tests](https://github.com/hed-standard/hed-tests). They have been moved to an independent repository so that more complete test suites can be developed.  We need to move the dependabot dependencies and modify the spec tests.