sources: add more site icons.

Add site icons for the following sites:

* 4chan
* Catbox
* Danbooru
* Drawcrowd
* E-Hentai
* Enty
* Gelbooru
* Hitomi
* Imgur
* Joyreactor
* Kemono Party
* Konachan
* Luscious.net
* Mega.nz
* Monappy
* Mihoyo
* Overdoll
* Pinterest
* Rule34.us
* Sankaku Complex
* Steam
* Webmshare
* Yande.re
* Zerochan

These are mainly used for source links on the https://danbooru.donmai.us/post_events?search[category]=Replacement page.

app/logical/source/url/rule34_dot_us.rb

@@ -11,6 +11,10 @@ class Source::URL::Rule34DotUs < Source::URL
     url.domain.in?(%w[rule34.us])
   end
 
+  def site_name
+    "Rule34.us"
+  end
+
   def parse
     case [domain, *path_segments]