Pomsky playground

This is the React app with the interactive Pomsky playground.

TODO

• Replace "Pomsky" label with "Editor Settings" in sidebar
• Proper Find & Replace functionality
• Locally save multiple files in localStorage, display as tabs
• Compile PCRE2 to wasm to run tests with PCRE2 on the web
• Don't highlight braces of text blocks
• Put error list somewhere else?