Upgrade to FontAwesome 5 (take two) (#6673)

* Add missing icons to set

* Revert FA5 revert

 This reverts commit 42572ff

* use new SVG syntax in locales

* Noscript page changes (remove login button, center "powered by" footer text)

* Cast wider net for SVG icons in settings

- include any _icon setting for SVG registry (offers better support for plugin settings)

- let themes store multiple pipe-delimited icons in a setting

- also replaces broken onebox image icon with SVG reference in cooked post processor

* interpolate icons in locales

* Fix composer whisper icon alignment

* Add support for stacked icons

* SECURITY: enforce hostname to match discourse hostname

This ensures that the hostname rails uses for various helpers always matches
the Discourse hostname

* load SVG sprite with pre-initializers

* FIX: enable caching on SVG sprites

* PERF: use JSONP for SVG sprites so they are served from CDN

This avoids needing to deal with CORS for loading of the SVG

Note, added the svg- prefix to the filename so we can quickly tell in
dev tools what the file is

* Add missing SVG sprite JSONP script to CSP

* Upgrade to FA 5.5.0

* Add support for all FA4.7 icons

- adds complete frontend and backend for renamed FA4.7 icons

- improves performance of SvgSprite.bundle and SvgSprite.all_icons

* Fix group avatar flair preview

- adds an endpoint at /svg-sprites/search/:keyword

- adds frontend ajax call that pulls icon in avatar flair preview even when it is not in subset

* Remove FA 4.7 font files

lib/tasks/svg_icons.rake

@@ -0,0 +1,38 @@
+def vendor_svgs
+  "#{Rails.root}/vendor/assets/svg-icons"
+end
+
+def library_src
+  "#{Rails.root}/node_modules"
+end
+
+task 'svgicons:update' do
+
+  yarn = system("yarn install")
+  abort('Unable to run "yarn install"') unless yarn
+
+  dependencies = [
+    {
+      source: '@fortawesome/fontawesome-free/sprites',
+      destination: 'fontawesome',
+    }
+  ]
+
+  start = Time.now
+
+  dependencies.each do |f|
+    src = "#{library_src}/#{f[:source]}/."
+
+    unless f[:destination]
+      filename = f[:source].split("/").last
+    else
+      filename = f[:destination]
+    end
+
+    dest = "#{vendor_svgs}/#{filename}"
+
+    FileUtils.cp_r(src, dest)
+  end
+
+  STDERR.puts "Completed copying dependencies: #{(Time.now - start).round(2)} secs"
+end