Add stt smart picker

[MB-Finski]

This pr imports the stt smart picker functionality from the stt_helper.

Again I tried to keep the refactoring to a minimum, although, I had some hesitation about doing some refactoring for the notification flow (since you cannot use the tasks like they are used for text processing notifications).

[julien-nc]

Nice!
Whenever we add a migration step, it's better to bump the app version number so we make sure the step is triggered when people test the PR (i was confused for a moment).
A few minor changes and we're good to go.

[julien-nc]

Is this component going to be used in other contexts than STT? If not, we could rename it to SttResultModal.

[MB-Finski]

I must admit, I have no other definite use case for a plain text result page yet but I ventured a guess here that we might have those in the future (for example, notifications where we want to hide which text processing task type was responsible for the result) . Although, it might also be that such features would be otherwise accommodated in the notification logic?

EDIT: The copywriter functionality might be one such example where we don't want to display the result as a "free prompt" result although we're bound to use that task type as the backend.

[julien-nc]

Anyway, not a big deal. Rename it if you want, merge if you don't 😁