VR Starter Tutorial rewrite/refactor (#2774)

* Initial VR starter tutorial rewrite

* More refactoring work on the VR starter tutorial. Moved the VR starter tutorial into its own sub directory and broke the tutorial into two parts

* Finished the first draf on most of the first part of the VR starter tutorial

* First draft for the first half of the VR tutorial is done! Now all that is left is the second half, which should be a tad easier to do

* About a fourth of the way through the refactor of the VR Starter tutorial part 2

* Almost finished part 2 of the VR starter tutorial rewrite. Just a little bit left

* Finished the second part of the VR starter tutorial rewrite

* Made small changes to the VR starter tutorial based on feedback from BastiaanOlij. Fixed merge conflict in PR

tutorials/vr/index.rst

@@ -6,4 +6,4 @@ VR
    :name: toc-tutorials-vr
 
    vr_primer
-   vr_starter_tutorial
+   vr_starter_tutorial/index

tutorials/vr/vr_starter_tutorial/index.rst

@@ -0,0 +1,9 @@
+VR Starer tutorial
+==================
+
+.. toctree::
+   :maxdepth: 1
+   :name: doc_vr_starter_tutorial
+
+   vr_starter_tutorial_part_one
+   vr_starter_tutorial_part_two