Strings args do not need to be parsed.

```
def test(a, b):
print(a, b)

if __name__ == "__main__":
fire.Fire(test)
```

`python .\test.py 1 '2 3'`
```1 2 3```

`python .\test2.py 1 '""2 3""'`
`1 2 3`

`python .\test.py 1 '--2 3'`
```ERROR: The function received no value for the required argument: b```

`python .\test.py 1 '\"2 3\"'`
```
1 "2
ERROR: Could not consume arg: 3"
```

`python .\test.py 1 '\"\"2 3\"\"'`
`1 ""2 3""`

The correct behavior should be equivalent to `print(1, "2 3")`, so strings args do not need to be parsed.

Reproduce the reported cases with the test.py example and the shown command-line arguments, starting at the fire.Fire(test) entry point. Trace how quoted string arguments are handled, then add coverage for the expected print(1, "2 3") behavior and verify that the existing examples still work.

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