multiple customers have reported characters not being rendered in the web terminal until Enter is clicked.

we've tracked this down to a regression in the webgl package, which can be found here: xtermjs/xterm.js#4665. webgl was introduced in Coder version 2.1.4 #9320. to fix this, we should default back to the previous rendering binary canvas, and create a deployment-wide flag to opt-in to webgl. the webgl regression should be fixed in upcoming versions of Chrome.