enhancement(Collapsible) additional styling for leading badge in coll…

[gselderslaghs]

Proposed changes

Implemented leading badge in Collapsible component

• Implemented the class "leading": this class will place the badge at the most left position in the collapsible element

Codepen:

Codepen example

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to change).

Checklist:

• I have read the CONTRIBUTING document.
• My commit messages follows the conventional commit format
• My change requires a change to the documentation
• My change requires a change to the documentation and updated it accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[wuda-io]

css variables for the margins would be cool. I don't know if there are specs from M3 but nevertheless, good work!