BUG: Raise ValueError for non-string columns in read_json orient='table' (GH19129)
- Closes #19129
- Adds validation to ensure all column names are strings when using orient='table' in read_json
- Raises a clear ValueError if invalid column names are found
- Adds a new unit test to pandas/tests/io/json/test_json_table_schema.py to cover the invalid input case
- Ran pytest and pre-commit hooks successfully

Looking forward to feedback. Thanks!
pre-commit.ci autofix Hi, it seems there is already a PR #60945 addressing this issue. This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. As mentioned, it appears we already have https://github.com/pandas-dev/pandas/pull/60945 addressing this issue so closing in favor of that PR since it was opened first 