Tab key should insert a tab character, not spaces, in markdown mode.

The "Preview emojis, mentions, and markdown syntax as you type" Beta feature has changed the behavior of the tab key in a markdown box.  If you disable that feature and press the tab key while inside of a code block it will insert a tab character.  If you enable that feature and press the tab key while inside of a code block it will instead insert 2 spaces.

I understand that some people like to indent with spaces, and if there was an option in Discord to choose tab key behavior and change it to spaces instead of a tab character that would be fine.  However, without such a feature I strongly believe that the default behavior of the tab key is that it should do what it says on the can, which is to insert a tab character.