Something like `pdf-engine: tinytex` should fail validation and we should limit valid values to pdf engines that we know and support.

See #5677

List of engines:
https://github.com/quarto-dev/quarto-cli/blob/912a8ac65dea297cc01082419d66e3535fbc84e5/src/config/pdf.ts#L73C1-L76
dragonstyle
2023-05-25T20:39:39Z
dragonstyle
bug yaml-validation latex
v1.4
open
Add schema validation to limit allowed types of `pdf-engine`
https://github.com/quarto-dev/quarto-cli/issues/5690