peopleAutocomplete: Use `user_id` as key for each item in list.
peopleAutocomplete: Use `user_id` as key for each item in list.

Two user might have same name, but can't have same `user_id`. So use
id as key for each item of the list which is unique.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile