Fix bug in IntegerValidator when an array contains both strings and integers, and add tests for IntegerValidator extras

[marthacryan]

Follow-up PR to #4612. Adds basic tests for passing and rejecting - also fixes a bug found while testing where the integer validator threw an error when arrays contained both strings and integers.

Code PR

• [x] I have read through the contributing notes and understand the structure of the package. In particular, if my PR modifies code of plotly.graph_objects, my modifications concern the codegen files and not generated files.
• [x] I have added tests (if submitting a new feature or correcting a bug) or modified existing tests. ~~- [ ] For a new feature, I have added documentation examples in an existing or new tutorial notebook (please see the doc checklist as well).~~
• [x] I have added a CHANGELOG entry if fixing/changing/adding anything substantial. - [ ] For a new feature or a change in behaviour, I have updated the relevant docstrings in the code to describe the feature or behaviour (please see the doc checklist as well).

[archmoj]

Please rename the title of the PR to indicate that this is a bug fix. Also please add a changelog entry.

- [ ] I have added a CHANGELOG entry if fixing/changing/adding anything substantial

[marthacryan]

Please rename the title of the PR to indicate that this is a bug fix. Also please add a changelog entry.

- [ ] I have added a CHANGELOG entry if fixing/changing/adding anything substantial

@archmoj Added! How does it look?