Release v0.20.0

[sebcrozet]

Added

• Add the RigidBodyDisabled and ColliderDisabled component that can be inserted to disable a rigid-body
  or collider without removing it from the scene.

Fix

• Fix spawn position of colliders without rigid bodies.
• Fix overriding enabled flag in debug render.

Modified

• Make debug-rendering enabled by default when inserting the RapierDebugRenderPlugin plugin with its default configuration.
• The debug-render feature has been replaced by two features: debug-render-2d and debug-render-3d. For example,
  using debug-render-2d with bevy_rapier3d, the debug-render will work with 2D cameras (useful, e.g., for top-down games
  with 3D graphics).
• In order to facilitate the use of bevy_rapier in headless mode, the AsyncCollider and AsyncSceneCollider
  components were moved behind the async-collider feature (enabled by default). Disabling that feature will
  make bevy_rapier work even with the MinimalPlugins inserted insetad of the DefaultPlugins.
• Corrected an API inconsistency where bevy_rapier components would sometimes require an InteracitonGroup type defined in
  rapier. It has been replaced by the CollisionGroup type (defined in bevy_rapier).
• Velocity::zero,linear,angular are now const-fn.