Switch from unmaintained paperclip to kt-paperclip (#16724)

* Switch from unmaintained paperclip to kt-paperclip

* Drop some compatibility monkey-patches not required by kt-paperclip

* Drop media spoof check monkey-patching

It's broken with kt-paperclip and hopefully it won't be needed anymore

* Fix regression introduced by paperclip 6.1.0

* Do not rely on pathname to call FastImage

* Add test for ogg vorbis file with cover art

* Add audio/vorbis to the accepted content-types

This seems erroneous as this would be the content-type for a vorbis stream
without an ogg container, but that's what the `marcel` gem outputs, so…

* Restore missing for_as_default method

* Refactor Attachmentable concern and delay Paperclip's content-type spoof check

Check for content-type spoofing *after* setting the extension ourselves, this
fixes a regression with kt-paperclip's validations being more strict than
paperclip 6.0.0 and rejecting some Pleroma uploads because of unknown
extensions.

* Please CodeClimate

* Add audio/vorbis to the unreliable set

It doesn't correspond to a file format and thus has no extension associated.

lib/paperclip/attachment_extensions.rb

@@ -6,6 +6,35 @@ module Paperclip
       instance_read(:meta)
     end
 
+    # monkey-patch to avoid unlinking too avoid unlinking source file too early
+    # see https://github.com/kreeti/kt-paperclip/issues/64
+    def post_process_style(name, style) #:nodoc:
+      raise "Style #{name} has no processors defined." if style.processors.blank?
+
+      intermediate_files = []
+      original = @queued_for_write[:original]
+      # if we're processing the original, close + unlink the source tempfile
+      intermediate_files << original if name == :original
+
+      @queued_for_write[name] = style.processors.
+                                inject(original) do |file, processor|
+        file = Paperclip.processor(processor).make(file, style.processor_options, self)
+        intermediate_files << file unless file == original
+        file
+      end
+
+      unadapted_file = @queued_for_write[name]
+      @queued_for_write[name] = Paperclip.io_adapters.
+                                for(@queued_for_write[name], @options[:adapter_options])
+      unadapted_file.close if unadapted_file.respond_to?(:close)
+      @queued_for_write[name]
+    rescue Paperclip::Errors::NotIdentifiedByImageMagickError => e
+      log("An error was received while processing: #{e.inspect}")
+      (@errors[:processing] ||= []) << e.message if @options[:whiny]
+    ensure
+      unlink_files(intermediate_files)
+    end
+
     # We overwrite this method to support delayed processing in
     # Sidekiq. Since we process the original file to reduce disk
     # usage, and we still want to generate thumbnails straight