Set up samples for 2021.2.0b4

Packages/manifest.json

     "com.unity.ide.visualstudio": "2.0.9",
     "com.unity.ide.vscode": "1.2.3",
     "com.unity.postprocessing": "3.1.1",
-    "com.unity.render-pipelines.high-definition": "11.0.0",
+    "com.unity.render-pipelines.high-definition": "12.0.0",
     "com.unity.test-framework": "1.1.27",
     "com.unity.timeline": "1.6.1",
     "com.unity.xr.legacyinputhelpers": "2.1.7",

ProjectSettings/ProjectVersion.txt

-m_EditorVersion: 2022.1.0a2
-m_EditorVersionWithRevision: 2022.1.0a2 (30d6875d3ce8)
+m_EditorVersion: 2021.2.0b4
+m_EditorVersionWithRevision: 2021.2.0b4 (af9ec38f7da3)

ProjectSettings/VFXManager.asset

   m_FixedTimeStep: 0.016666668
   m_MaxDeltaTime: 0.05
   m_CompiledVersion: 3
-  m_RuntimeVersion: 20
+  m_RuntimeVersion: 19
   m_RuntimeResources: {fileID: 11400000, guid: bc10b42afe3813544bffd38ae2cd893d, type: 2}