Abstract userToAutocompleteOption everywhere in the frontend

Description

Currently we have a lot of places where we have an autocomplete of users (see examples below). The problem is that each of these places have their own userToAutocompleteOption, several of which are implemented differently from each other. We wanna standardize how each of these places uses this method then, abstract it into a single method and put it in a new users.utils.ts file in the utils folder. (you'll probably need two versions of this method, one with the user's role and one without)

Acceptance Criteria

All of the places where userToAutocompleteOption is used have been abstracted as much as possible and are implemented the same way (returning an option with this form: { label: string; id: string }, so that it can be used by the NERAutocomplete component)

Proposed Solution

Abstract everywhere this method (might even be a couple more spots with a slightly different name), and pull the abstracted method out in a file in the utils folder.

Mocks

Examples of user autocompletes:

Search the frontend for userToAutocompleteOption and similarly named helpers, then compare every user autocomplete implementation. Add the shared versions to a new users.utils.ts file and ensure each site supplies an option shaped as { label: string; id: string } for NERAutocomplete, including variants with and without the user's role.