Update the wand icon used in the Panel Application

There is a Silk icon in the box to provide a tip about the use of Panels.

Ideally:

• the wand icon would be mapped to `fa-magic` in FA (see https://fontawesome.bootstrapcheatsheets.com/)
• the icon syntax would use the current icontheme and not always Silk.
• the meaningless box could be replaced with an information message