Change textarea to only trigger change on change event

About the fix

This is a bit different to how it's described in the ticket, but I remember we talked about it as a possible fix in the sprint planning, so I've done as such for now

Instead of triggering the change event on typing (as it currently is), I changed the textarea component to implement ControlValueAccessor, and now it's only triggering on the change event (which gets called on blur for example)

Please comment though if this solution isn't ideal, I could make another merge request solving it as suggested in the issue description

Closes #508 (closed)