Util/helper for state that is a set

## Describe the task

We have frequently found that we want a set of x, with a command to add and remove, and a reducer to execute that. Is it worth looking at building a generic or code gen, etc. that makes this more direct and ensures consistency.

No files, tests, or entry points are named. Start by reviewing existing state patterns for sets, including their add/remove commands and reducers, then determine whether a shared utility or code generation approach is appropriate. Done means an agreed, consistent design and an implementation path, but the issue does not define the expected API or behavior.

Escrita pelo modelo de indexação a partir do texto da issue.