Fixes typo in the `body_view` reference in `RigidObject` (#240)

This MR fixes a typo in `RigidObject` where for a rigid object, the private member `_body_view` is not defined (since it should be using the `root_view`). The fix changes the reference to be the public `body_view` property.

- Bug fix (non-breaking change which fixes an issue)

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with `./orbit.sh --format`
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my feature works
- [x] I have updated the changelog and the corresponding version in the extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already exists there

source/extensions/omni.isaac.orbit/config/extension.toml

 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "0.9.38"
+version = "0.9.39"
 
 # Description
 title = "ORBIT framework for Robot Learning"

source/extensions/omni.isaac.orbit/docs/CHANGELOG.rst

 Changelog
 ---------
 
+0.9.39 (2023-11-08)
+~~~~~~~~~~~~~~~~~~~
+
+Fixed
+^^^^^
+
+* Changed the reference of private `_body_view` variable inside the :class:`RigidObject` class
+  to the public `body_view` property. For a rigid object, the private variable is not defined.
+
+
 0.9.38 (2023-11-07)
 ~~~~~~~~~~~~~~~~~~~
 

source/extensions/omni.isaac.orbit/omni/isaac/orbit/assets/rigid_object/rigid_object.py

@@ -116,7 +116,7 @@ class RigidObject(AssetBase):
         """
         # write external wrench
         if self.has_external_wrench:
-            self._body_view._physics_view.apply_forces_and_torques_at_position(
+            self.body_physx_view.apply_forces_and_torques_at_position(
                 force_data=self._external_force_b.view(-1, 3),
                 torque_data=self._external_torque_b.view(-1, 3),
                 position_data=None,