Code Syntax Highlighting

Please make sure the code-highlight feature is enabled before testing!

See also engine!485 (merged), front!735 (merged)

Closes minds#864

What's inside:

• Adds react-native-syntax-highlighter to handle code highlighting on posts and comments
• Adds highlight.js and parse5 to handle Blog HTML code highlighting
• Adds code-highlight.service
  • Posts/Comments: Handles code fence detection and uses react-native-syntax-highlighter to highlight code
  • Blogs: Handles HTML <pre><code> detection via parse5 and highlights using highlight.js
• Adds highlightCodeBlocks boolean prop to <Tags /> component