Change "Clear form after search" logic

Problem/Motivation

If the "Clear form after search" option is selected, the entered question gets cleared immediately on submit.
For usability reasons, it would be better to change to current logic and keep the question visible until we get a response from the back-end.
Context: for end users it might seem like they did something wrong if they don't immediately see an answer pop up.

Proposed resolution

If the "Clear form after search" option is selected:
* When submitting the question form, the entered question itself stays visible during the "loading" animation.
* When the response (or first tokens) get streamed, the questions disappears, to make room for follow up questions.

If the "Clear form after search" option is NOT selected:
No changes needed.