Change default behavior and combo box values in XRInterface plugin

The XRInterface menu in XR mode had several parameters where the initially displayed combobox values did not match the actual values.
The correct values are now set upon launching the XR mode.

Additionally, the initial View Up direction is now based on what is displayed in the Render View before launching XR mode.
Lastly, the default trigger action is changed to Pick mode instead of Probe mode (more suitable as default behavior).