ENH: Add template support for Quick Reply

[johnhenley]

Is your feature request related to a problem?

In order to properly implement a better layout for quick reply, replace current hard-coded control with templated control. Move current hard-coded HTML to default template, and template editor. That will support implementing pull requests for this issue:
Currently the Quick reply box does not work very well on mobile..

Describe the solution you'd like

Make sure it's as easy to use as possible on Mobile. :-)

Additional context

The quick reply editor is wrapped in a table, we should really use div and flexbox here so we can make sure the title is above the text box and the text box is full width..

Originally posted by @Timo-Breumelhof in #305