Merge branch 'scss-url-linters' into 'master'

Enable the UrlFormat and UrlQuotes SCSS Linters.

There were no lints to fix for this one, so it's just preventative.

UrlFormat: URLs should be valid and not contain protocols or domain names.

UrlQuotes: URLs should always be enclosed within quotes.

cc: @jschatz1 

See merge request !3770

.scss-lint.yml

@@ -244,11 +244,11 @@ linters:
   
   # URLs should be valid and not contain protocols or domain names.
   UrlFormat:
-    enabled: false
+    enabled: true
 
   # URLs should always be enclosed within quotes.
   UrlQuotes:
-    enabled: false
+    enabled: true
 
   # Properties, like color and font, are easier to read and maintain
   # when defined using variables rather than literals.