cardigannIndexer: add validate field filter

will mostly be used with sites that used tags, to remove the non-genre chaff from the genre field.

src/Jackett.Common/Definitions/schema.json

@@ -796,7 +796,7 @@
             "properties": {
                 "name": {
                     "type": "string",
-                    "enum": ["querystring", "timeparse", "dateparse", "regexp", "re_replace", "split", "replace", "trim", "prepend", "append", "tolower", "toupper", "urldecode", "urlencode", "timeago", "reltime", "fuzzytime", "validfilename", "diacritics", "jsonjoinarray", "hexdump", "strdump"]
+                    "enum": ["querystring", "timeparse", "dateparse", "regexp", "re_replace", "split", "replace", "trim", "prepend", "append", "tolower", "toupper", "urldecode", "urlencode", "timeago", "reltime", "fuzzytime", "validfilename", "diacritics", "jsonjoinarray", "hexdump", "strdump", "validate"]
                 },
                 "args": {
                     "oneOf": [

src/Jackett.Common/Indexers/CardigannIndexer.cs

@@ -1129,6 +1129,14 @@ namespace Jackett.Common.Indexers
                             strTag = ":";
                         logger.Debug(string.Format("CardigannIndexer ({0}): strdump{1} {2}", Id, strTag, DebugData));
                         break;
+                    case "validate":
+                        char[] delimiters = { ',', ' ', '/', ')', '(', '.' };
+                        var args = (string)Filter.Args;
+                        var argsList = args.ToLower().Split(delimiters, System.StringSplitOptions.RemoveEmptyEntries);
+                        var validList = argsList.ToList();
+                        var validIntersect = validList.Intersect(Data.ToLower().Split(delimiters, System.StringSplitOptions.RemoveEmptyEntries)).ToList();
+                        Data = string.Join(", ", validIntersect);
+                        break;
                     default:
                         break;
                 }