User search previously filtered bots only when they happened to match the
search string. That produced two bad behaviours:
1. Bots owned by other users could surface on an exact-username match,
leaking them into assignee pickers and similar UI.
2. A user could not reliably find their own bots by typing a partial
name, so bots became awkward to assign to tasks.
Change ListUsers to treat bot ownership explicitly: the existing match
branch excludes rows owned by someone else, and a second branch always
returns bots owned by the calling user. The own-bots branch also
respects any AdditionalCond passed in so project-scoped listings don't
start leaking bots from outside the project.
This adds a feature where you can enable users to only find members of teams they're part of. This makes the user search when sharing projects less confusing, because users only see other users they already know.
It is still possible to add users to teams with their email address, if they have that enabled in the user settings.