Ability use args, kwargs with delimiter

Fire now try to parse flat args and kwargs, but often this not convenient
Example:

```
import fire

def test(*args, **kwargs):
print(kwargs)
print(args)

fire.Fire(test)

```

`python main.py arg1 arg2 --kwarg1 1 --kwarg2 2`

`
{'kwarg1': 1, 'kwarg2': 2}
('arg1', 'arg2')
`

In some cases will be much more simple have opportunity to set *args **kwargs like this :
`
python main.py --args arg1 --args arg2 --kwargs kwarg1=1 --kwargs kwarg2=2
`

Start by reproducing the issue's `python main.py` examples and inspect Python Fire's argument-parsing entry point. Determine how repeated `--args` and `--kwargs` values should map to positional and keyword arguments, including their value types. Done means the proposed syntax works without regressing the existing flat argument and keyword syntax.

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