Updated spec tests and description of Duration handling (#621)

* Updated test versions to 8.3.0 and clarified conditions for TAG_INVALID

* Merged NODE_NAME_EMPTY into TAG_INVALID

* Corrected additional NODE_NAME_EMPTY_LINKS

* Lower the schema version on two tests back

* Made hed_error_codes.json only contain codes with json files

* Add hedID validation tests

* Updated some of invalid characters

* Updated the JSON tests to have all fields

* Updated tests to include warning and alt_code in non-schema tests

* Updated the tests with additional alt-codes

* Definition may have no inner group

* Minor update in appendix B errors

* Minor changes to tests

* Corrected a typo in the specification

* Correction to curly brace test

* Modified the test for definition with no group

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Co-authored-by: IanCa <ianrcallanan@gmail.com>