jinja : implement mixed type object keys (#18955)
* implement mixed type object keys
* add tests
* refactor
* minor fixes
* massive refactor
* add more tests
* forgotten tuples
* fix array/object is_hashable
* correct (albeit broken) jinja responses
verified with transformers
* improved hashing and equality
* refactor hash function
* more exhausive test case
* clean up
* cont
* cont (2)
* missing cstring
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Co-authored-by: Xuan Son Nguyen <son@huggingface.co>
