formatter: preserve case of hashtags

when generating hashtag links, we used the casefolded version that we use in
the link URLs, instead of the original version.

accordingly, adjust the formatter to use the original text for the links, while
keeping the casefolded version for the URLs.

lib/pleroma/formatter.ex

@@ -244,8 +244,8 @@ def add_hashtag_links({subs, text}, tags) do
 
     subs =
       subs ++
-        Enum.map(tags, fn {_, tag, uuid} ->
-          url = "<a href='#{Pleroma.Web.base_url()}/tag/#{tag}' rel='tag'>##{tag}</a>"
+        Enum.map(tags, fn {tag_text, tag, uuid} ->
+          url = "<a href='#{Pleroma.Web.base_url()}/tag/#{tag}' rel='tag'>#{tag_text}</a>"
           {uuid, url}
         end)