Bring element to front on drag in demo

[emattheis]

Breaking Change

• no breaking changes

Proposed Change

• update the demo page to bring elements to the top when dragged - i.e., z-index of the dragged element is higher than other draggable elements

Type of Change

• Demo Functionality (code that only affects the demo HTML page)
• Bugfix (non-breaking change that resolves an issue)
• New Feature (which introduces functionality to an existing function)
• New Function (a new way to do something, for example make a pane of glass)
• Breaking Change (fix or feature that disrupts existing functionality)

Additional Information

• This PR addresses or resolves issue: N/A
• This PR is related to issue: N/A

Checklist

• All code is thoroughly tested and functions locally.
• There is minimal to no commented-out code in this PR.