Support `typing.Literal` as type of tool parameters or return value
Author: grf53
Pull request: yes

# What does this PR do?

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This PR adds support for using `typing.Literal` as a type hint of tool function written in python.

I realized that using `typing.Literal` for argument's type hint is currently not supported during my tries to use tools as the python function(referring [Document 'Tools and RAG'](https://huggingface.co/docs/transformers/v4.51.3/en/chat_extras)).

The error I got is:
```
in _parse_type_hint
    raise TypeHintParsingException("Couldn't parse this type hint, likely due to a custom class or object: ", hint)
transformers.utils.chat_template_utils.TypeHintParsingException: ("Couldn't parse this type hint, likely due to a custom class or object: ", typing.Literal[...])
```

Fortunately, there is already a feature to deal with the 'complex' type hints like `list[str]`, `Union[List[int], Dict[int, str]]`.
So I just added case for `origin is Literal`, just putting its `args` as value of the key `"enum"` in json schema is fine.

Putting `"type"` in that was not a good idea, because we could accidentally filter a valid case when the types are heterogeneous in `args`. But a rough type validation could be valuable for the case using no static typing tool.

Additionally, as I see, there was a glitch in the related function `_get_json_schema_type(param_type: str)`, which is that the type hint of argument `param_type` need to be `type` instead of `str`. This tiny change is also in this PR.

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Comments:
Yes, this seems like a good PR! Some things to check:

1) You're rendering `Literal` as an `enum` in the schema, which makes sense, but you should probably also set the `type`. I know it's not strictly required in JSON schema when you have an `enum`, but more templates understand types than enums, so it'll help! If you're worried about heterogenous types in an `enum`, you can just use the union of all the enum types: `"type": ["integer", "string"]`

2) Make sure to rebase and run `make fixup` or `make style` after `pip install -e .[quality]` to get tests to pass!

> 1. You're rendering `Literal` as an `enum` in the schema, which makes sense, but you should probably also set the `type`. I know it's not strictly required in JSON schema when you have an `enum`, but more templates understand types than enums, so it'll help! If you're worried about heterogenous types in an `enum`, you can just use the union of all the enum types: `"type": ["integer", "string"]`
> 2. Make sure to rebase and run `make fixup` or `make style` after `pip install -e .[quality]` to get tests to pass!

@Rocketknight1 
Thank you for kind suggestions!

1. Added `"type"` as union of the types of `args`
2. Done, so Circle CI tests are passed

PTAL!

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