feat: support regex in filter

Makes running css-loader with advanced filter settings in worker possible.

src/options.json

@@ -13,7 +13,16 @@
           "type": "object",
           "properties": {
             "filter": {
-              "instanceof": "Function"
+              "description": "Allows to custom `url()`/`image-set()` functions handling via regexp or function.",
+              "link": "https://github.com/webpack-contrib/css-loader#url",
+              "anyOf": [
+                {
+                  "instanceof": "RegExp"
+                },
+                {
+                  "instanceof": "Function"
+                }
+              ]
             }
           },
           "additionalProperties": false

src/utils.js

@@ -529,7 +529,9 @@ function getFilter(filter, resourcePath) {
     if (typeof filter === "function") {
       return filter(...args, resourcePath);
     }
-
+    if (filter instanceof RegExp) {
+      return filter.exec(...args);
+    }
     return true;
   };
 }