Components: Add disabled prop to CheckBoxControl

[im3dabasia]

What?

Adds support for disabled state in CheckboxControl.
Closes #59411

Why?

Issue #59364 identified the need for a disabled state on CheckboxControl for better accessibility and user experience in forms.

How?

1. Added styling for for the disabled state
2. Ensured onChange handler is bypassed when aria-disabled is true

Testing Instructions

1. Run npm run storybook:dev
2. Navigate to the CheckboxControl component
3. Test different disabled states and verify styling
4. Ensure disabled checkboxes cannot be toggled
5. Test keyboard navigation with both regular and focusable disabled checkboxes

Screencast

Screen.Recording.2025-03-27.at.3.23.01.PM.mov

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: im3dabasia <[email protected]>
Co-authored-by: mirka <[email protected]>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.