Blender Git Loki

UI: Add auto keyframing popover

For other areas in Blender that have a toggle and related settings,
we put a popover with the settings right next to the toggle. This
combination is nice because it organizes the settings without making
interaction slower. It also makes the settings more discoverable since
they're right next to the toggle.

Differential Revision: https://developer.blender.org/D8537