ENH: Implemented a check to test if filepath_or_buffer is a valid JSON string or a valid filepath and raises an error in the case that it is neither.
- [x] closes #29104 thread.
- [ ] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit) for how to run them
- [ ] whatsnew entry

ENH: Implemented a check to test if filepath_or_buffer is a valid JSON string or a valid filepath and raises an error in the case that it is neither. Per the thread in #29102 and related thread in #29104, there should be a way to differentiate between a json string passed as input and a file_path. We cannot just say that since a string is not a valid path, raise a FileNotFoundException. So this PR attempts to check intent.
Hello @cheungje! Thanks for opening this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:

* In the file [`pandas/io/json/_json.py`](https://github.com/pandas-dev/pandas/blob/56c338ee4ddc43584c34e5a901ec32e0986ada6c/pandas/io/json/_json.py):

> [Line 693:1](https://github.com/pandas-dev/pandas/blob/56c338ee4ddc43584c34e5a901ec32e0986ada6c/pandas/io/json/_json.py#L693): [W293](https://duckduckgo.com/?q=pep8%20W293) blank line contains whitespace
> [Line 730:89](https://github.com/pandas-dev/pandas/blob/56c338ee4ddc43584c34e5a901ec32e0986ada6c/pandas/io/json/_json.py#L730): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (89 > 88 characters)
> [Line 739:89](https://github.com/pandas-dev/pandas/blob/56c338ee4ddc43584c34e5a901ec32e0986ada6c/pandas/io/json/_json.py#L739): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (96 > 88 characters)



 Please open only one pr. You can easily push this to your other pr