Include www.youtube.com as Youtube host (#1028)

Task/Issue URL:
https://app.asana.com/0/1204099484721401/1208593005609709/f
iOS PR:  duckduckgo/iOS#3455
macOS PR: duckduckgo/macos-browser#3434
What kind of version bump will this require?: Minor

**Description**:
We were missing www.youtube.com as a valid host for Youtube.

Sources/DuckPlayer/DuckPlayerURLExtension.swift

@@ -155,7 +155,7 @@ extension URL {
 
     public var isYoutube: Bool {
         guard let host else { return false }
-        return host == "m.youtube.com" || host == "youtube.com"
+        return host == "m.youtube.com" || host == "youtube.com" || host == "www.youtube.com"
     }
 
     public func addingWatchInYoutubeQueryParameter() -> URL? {