Description

Wrapping the return of CMB2->box_classes() in sanitize_html_class() per WP VIP Feedback.

Motivation and Context

Sanitizes the class of the CMB2 box.

Risk Level

Minimal risk

Testing procedure

1. Add filter to cmb2_wrap_classes to add some class names with quotes or special characters.
2. Create CMB2 metabox.
3. Check CMB2 metabox classes.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the code style of this project.
• My code and pull requests meets the Contributing guidelines.