New filter: List open polls (polls that the poll participant did not participate in yet)

⚠️ This issue respects the following points: ⚠️

• I agree to follow Nextcloud's Code of Conduct.

Describe the goal you'd like to achieve

As a poll participant, I want to be able to see a list of my open polls (polls that I not participated in yet), because it helps to get a better overview over the existing polls that I have to participate in.
It also serves as the opposing version of the "participated" view/filter.

Describe possible solutions

I suggest to just add a new filter view, exactly like the "participated" view, and adjust the filter condition accordingly.
You probably have a raw icon version of the participated icon.
I suggest that you remove the checkmark from the participated icon and add something that indicates that there is something to do. An exclamation mark is already used for the relevant polls view, but maybe something like a checkbox icon above the user icon? This indicates that after the poll participant answers the poll, it moves to the participated view, the view that looks almost the same, but just with a checkmark icon instead of the checkbox. I guess you have the best idea what this icon should look like so that it fits into your look and feel.

PS: If you prepare the icon for me I might be able to implement it myself.

Additional context

Our team has around 30 polls that apply to one year.
It is necessary that all polls get answered before the poll date.
It is not intuitive to find out which one of those 30 polls is still open.
The "participated" view is not helpful in this use case, because our users are mostly interested in unanswered polls.

Start by locating the existing “participated” view/filter and its icon in the poll app’s frontend. Follow its filtering and rendering behavior, then add the opposing unanswered-polls view with a distinct icon; done means participants can select it and see only polls they have not participated in yet.