DEV: Expand UploadMarkdown generation capabilities (#15930)

The chat quoting mechanism will need to be able to generate
markdown for all kinds of uploads. The UploadMarkdown class
was missing generation for video and audio uploads. This
commit adds that in, and also expands the server-side regex
recognition of FileHelper types to match those in uploads.js,
and adds a spec for UploadMarkdown

lib/file_helper.rb

@@ -17,6 +17,14 @@ class FileHelper
     filename.match?(supported_images_regexp)
   end
 
+  def self.is_supported_video?(filename)
+    filename.match?(supported_video_regexp)
+  end
+
+  def self.is_supported_audio?(filename)
+    filename.match?(supported_audio_regexp)
+  end
+
   def self.is_inline_image?(filename)
     filename.match?(inline_images_regexp)
   end
@@ -25,6 +33,10 @@ class FileHelper
     filename.match?(supported_media_regexp)
   end
 
+  def self.is_supported_playable_media?(filename)
+    filename.match?(supported_playable_media_regexp)
+  end
+
   class FakeIO
     attr_accessor :status
   end
@@ -151,11 +163,19 @@ class FileHelper
   end
 
   def self.supported_audio
-    @@supported_audio ||= Set.new %w{mp3 ogg wav m4a}
+    @@supported_audio ||= Set.new %w{mp3 ogg oga opus wav m4a m4b m4p m4r aac flac}
   end
 
   def self.supported_video
-    @@supported_video ||= Set.new %w{mov mp4 webm ogv}
+    @@supported_video ||= Set.new %w{mov mp4 webm ogv m4v 3gp avi mpeg}
+  end
+
+  def self.supported_video_regexp
+    @@supported_video_regexp ||= /\.(#{supported_video.to_a.join("|")})$/i
+  end
+
+  def self.supported_audio_regexp
+    @@supported_audio_regexp ||= /\.(#{supported_audio.to_a.join("|")})$/i
   end
 
   def self.supported_images_regexp
@@ -173,4 +193,12 @@ class FileHelper
         /\.(#{media.to_a.join("|")})$/i
       end
   end
+
+  def self.supported_playable_media_regexp
+    @@supported_playable_media_regexp ||=
+      begin
+        media = supported_audio | supported_video
+        /\.(#{media.to_a.join("|")})$/i
+      end
+  end
 end