refactor: break down json grammar parser in different files (#3004)

* refactor: break down json grammar parser in different files

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* fix: patch to `refactor_grammars` - propagate errors (#3006)

propagate errors around

Signed-off-by: Dave Lee <dave@gray101.com>

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Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Signed-off-by: Dave Lee <dave@gray101.com>
Co-authored-by: Dave <dave@gray101.com>