Fix and simplify FontAwesome integration

[ggrossetie]

• Use a npm task to generate fontawesome-icon-defs.js
• Use a fontawesome-icons.json to declare a list of icons to include in the bundle

  [
  {
  "prefix": "fas",
  "iconName": "fire"
  },
  {
  "prefix": "fas",
  "iconName": "exclamation-circle"
  }
  ]

• Upgrade to FontAwesome 6.4

[prudhomm]

indeed that would be great