DEV: Set application template plugin outlets to tagName="" (PR #10382)

GitHub

@eviltrout I think you said this was ok on plugin outlets before, but just want to double check. If this is OK I can drop the custom application template for the Teams plugin.

@awesomerobot it can be a breaking change if people are depending on those being divs in their CSS. Still, long term I would rather have fewer divs if we don’t need them. One thing you could do is merge when you know you will be around, then after it deploys check out some common plugins to make sure they render properly.