Version

Stable master

Describe the bug

Currently, we add styling specific to download icon inside the parent DownloadAttachment. microsoft/BotFramework-WebChat#2868, this PR will be consolidating Upload and Download attachment as a single FileAttachment at which point when Emulator upgrades to WebChat 4.8 the styling change made in #2068 for download icon would have no effect.

Expected behavior

When Emulator bumps Webchat dependency to 4.8 ensure that styling for download icon under download attachment is replaced with FileAttachment.