The main objective for this PR is to fix the issue where character controllers might get stuck against vertical walls.

• The kinematic character controller autostepping is now disabled by default.
• Add KinematicCharacterController::normal_nudge_factor used to help getting the character unstuck
  due to rounding errors.
• Rename TOI to ShapeCastHit.
• Rename many fields from toi to time_of_impact.
• The QueryPipeline::cast_shape method now takes a ShapeCastOptions instead of the max_toi
  and stop_at_penetration parameters. This allows a couple of extra configurations, including the
  ability to have the shape-cast target a specific distance instead of actual shape overlap.

Close #612
Fix #418
Fix #611
Fix dimforge/bevy_rapier#489