Returns the leads the token's user can see, newest first by default. Users who can see all
records get every lead in the company; sales users get the leads assigned to them and to the
reps they manage.

Results are paginated with page and per_page (default 25, maximum 100). Filter with q,
lead_stage_ids[], lead_types[], sales_rep_ids[] and stalled, and order with sort and
direction.

Alongside leads, the response includes stats (open, won and lost counts and the open pipeline
value across everything you can see), entered_at_by_id (when each lead entered its current
stage) and next_step_by_id (each lead's next to-do, where one exists).