Pr 2982 ci branch (#3046)

* Add json_schema alias for GrammarType

* Add tests for all aliases

* fix: various linter adjustments

* fix: end-of-file-fixer lint

* fix: add test snapshots and avoid docs change

* fix: another end-of-file-fixer lint

* feat: support json_schema grammar constraining and add tests

* fix: bump openapi doc with new grammar option

* fix: adjust test payload

* fix: bump test snaps

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Co-authored-by: Alex Weston <alexw@alkymi.io>