Improve the "Snippets Seeker" UI using Calcite

[hhkaos]

The Snippets Seeker is interface currently looks like this:

Proposed enhancements:

• Preselect "JavaScript" on start
• Replace the current interface with something more modern using Calcite UI Components
• Add code syntax highlighting using highlight.js
• Make sure it is responsive
• Introduce a text field allowing searching on any field (prefix, name, description, body) , we could use an external utility like json-find
• Replace the top banner with a step-by-step tour like intro.js (or similar tool) to be displayed the first time you enter, and in the subsequent times, if you click on a help icon.