Add a two-dimensional grid / an array of time and location/duty

⚠️ 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 owner, I want to be able to add a two-dimensional poll, because it helps to assign duties for e.g. a small festival at a school, etc.

Describe possible solutions

So for multiple times there are multiple options or a list of options to choose from.
Ideally you can specify the max number of votes/assignees per duty.

Top-down should be time of day
left-right should be the order of the duties by default

Caveat: there may be a different list of duties per time of day.

But the two axis could be switched if necessary / wanted for display purpose.
An additional plus would be to filter on a specific duty option / time row/column.

Additional context

I got the idea from a tool in german: www.standeinteilung.de

Here is an example from the setup & configuration screen

No files, tests, or entry points are named. Begin by surveying how polls, times, duties, votes, and assignee limits are represented and rendered, then define the data model and interaction design for the two-dimensional grid; done means the feature supports the described axes, per-cell limits, differing duties by time, axis switching, and filtering.