Add script to preview/validate Nerd Fonts (o2sh#1492)

.editorconfig

@@ -17,3 +17,7 @@ indent_style = tab
 [*.json]
 indent_style = space
 indent_size = 2
+
+[*.rb]
+indent_style = space
+indent_size = 2

scripts/nf-preview.rb

@@ -0,0 +1,15 @@
+#!/usr/bin/env ruby
+require "yaml"
+
+LANGUAGES_FILE = File.expand_path("../../languages.yaml", __FILE__)
+
+languages = YAML.safe_load_file(ARGV[0] || LANGUAGES_FILE, symbolize_names: true)
+
+languages.each do |language, attributes|
+  icon = attributes[:icon]
+  next if icon.nil?
+  match = /\A\\u\{([A-F0-9]{4,})\}\z/i.match(icon)
+  raise "Icon for #{language} is not in the correct format: `#{icon}`" unless match
+  glyph = match.captures[0].hex.chr("UTF-8")
+  puts "#{language}: #{glyph}"
+end