Allow entering text directly for origin trial feedback

[cbiesinger]

Is your feature request related to a problem? Please describe.
Currently, the "Origin trial feedback summary" is asking for a URL. But for features that only have a short feedback summary it would be more convenient to directly put the feedback into Chromestatus instead of creating a URL just for a short paragraph.

Describe the solution you'd like
Provide a textbox for OT feedback instead of just a URL

Additional context
Add any other context or screenshots about the feature request here.