Add Sass integration

We are still using the old `ruby-sass` because it's a dependency from
`rails-sass` which is a dependcy from `select2`. It looks like the
master branch on the ofn fork get rid of the dependency, so we should
upgrading.

Gemfile

@@ -126,6 +126,8 @@ gem 'angular_rails_csrf'
 
 gem 'jquery-rails', '4.4.0'
 gem 'jquery-ui-rails', '~> 4.2'
+# TODO move away from sass-rails, master branch will get rid of dependency, so we can move to
+# https://github.com/sass/embedded-host-node
 gem "select2-rails", github: "openfoodfoundation/select2-rails", branch: "v349_with_thor_v1"
 
 gem 'good_migrations'

package.json

@@ -31,6 +31,7 @@
     "postcss-import": "^16.1.1",
     "postcss-loader": "^8.2.0",
     "postcss-preset-env": "^10.5.0",
+    "sass-loader": "^16.0.6",
     "select2": "*",
     "shortcut-buttons-flatpickr": "*",
     "stimulus": "*",

yarn.lock

@@ -6811,6 +6811,13 @@ safe-regex-test@^1.1.0:
   resolved "https://registry.yarnpkg.com/safer-buffer/-/safer-buffer-2.1.2.tgz#44fa161b0187b9549dd84bb91802f9bd8385cd6a"
   integrity sha512-YZo3K82SD7Riyi0E1EQPojLz7kpepnSQI9IyPbHHg1XXXevb5dJI7tpyN2ADxGcQbHG7vcyRHk0cbwqcQriUtg==
 
+sass-loader@^16.0.6:
+  version "16.0.6"
+  resolved "https://registry.yarnpkg.com/sass-loader/-/sass-loader-16.0.6.tgz#913b05607d06c386bc37870494e1e3a3e091fd3b"
+  integrity sha512-sglGzId5gmlfxNs4gK2U3h7HlVRfx278YK6Ono5lwzuvi1jxig80YiuHkaDBVsYIKFhx8wN7XSCI0M2IDS/3qA==
+  dependencies:
+    neo-async "^2.6.2"
+
 sax@^1.4.1:
   version "1.4.3"
   resolved "https://registry.yarnpkg.com/sax/-/sax-1.4.3.tgz#fcebae3b756cdc8428321805f4b70f16ec0ab5db"