DOC: Group optional dependencies by category
- [x] closes #39594 
- [ ] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry

This PR splits the Optional Dependencies table into multiple tables one for each category. It should help people compare different options when looking for a specific capability, e.g. "I need to read an Excel file. What are my options?".

The specific grouping felt pretty subjective. If you think of a better way to group them, we can do that instead.