BUG: to/read_* do not use user-provided file handle if handle implements os.PathLike and also opened the file
- [x] I have checked that this issue has not already been reported.

- [ ] I have confirmed this bug exists on the latest version of pandas (theoretically affected as well but my example doesn't work for <1.2 (need binary file handle) other examples should trigger this bug in <1.2).

- [x] (optional) I have confirmed this bug exists on the master branch of pandas.

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#### Code Sample, a copy-pastable example

```python
import os

import fsspec
import pandas as pd

# create a 'normal' file handle
with open("abc.test", mode="w") as open_obj:
    assert not isinstance(open_obj, os.PathLike)  # is not converted to a string
    position = open_obj.tell()

    # let to_csv write to the opened file
    pd.DataFrame({"a": [1, 2, 3]}).to_csv(open_obj)

    # the position of the file buffer should have changed if to_csv used it
    assert open_obj.tell() != position


# create a file handle that also implements os.PathLike/has __fspath__
fsspec_obj = fsspec.open("file://abc.test", mode="wb").open()
with fsspec_obj:
    assert isinstance(fsspec_obj, os.PathLike)  # is converted to a string
    position = fsspec_obj.tell()

    # let to_csv write to the opened file
    pd.DataFrame({"a": [1, 2, 3]}).to_csv(fsspec_obj)

    # the position of the file buffer should have changed if to_csv used it
    assert fsspec_obj.tell() != position  # fails
```

#### Problem description

`get_filepath_or_buffer` (<1.2) or `get_handle` (1.2) call `stringify_path` to convert `pathlib.Path` and other `os.PathLike` to a string. This string is then later opened. It seems that there is at least one file object that implements `os.PathLike` but at the same time already opens the file. In this case case, all `to/read_*` that use `get_handle` (or `get_filepath_or_buffer` in <1.2) extract the string and then open the file (even though the user already opened it).

I'm not sure whether there are other examples. I will look into how to fix this.