ENH: added an optional css id to `<table>` tags created by `frame.to_html`
This is useful for the reasons mentioned in #8496

- Automatically create a random id for tables created using `_repr_html_` using uuid.
- Also updated `test_repr_html_float` to be more descriptive and avoid conflicts with random numbers in the id for`_repr_html_`

- [x] closes #8496
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry
