Move Screen Space Shadow to multicompile and remove config requirement for DXR (#960)

* Change code to have a indirectDiffuseMode and start to clean RaytracingMacro

* Little extra cleanup

* Clean area shadow code and remove usless macro

* update shader config files for projects

* Better naming for SKIP_RASTERIZED_AREA_SHADOWS

* Update Upgrading-from-2020.1-to-2020.2.md

* remove useless comment

* cleanup have deferred rendering

* Clean RaytracingIndirectDiffuse.compute code

* Move screen space shadow to a multicompile + remove Raytracing macro

* Remove config package from DXR Test

Author: sebastienlagarde

TestProjects/HDRP_DXR_Tests/LocalPackages/com.unity.render-pipelines.high-definition-config/Runtime.meta

@@ -11,7 +11,7 @@
         "com.unity.purchasing": "2.0.6",
         "com.unity.render-pipelines.core": "file:../../../com.unity.render-pipelines.core",
         "com.unity.render-pipelines.high-definition": "file:../../../com.unity.render-pipelines.high-definition",
-        "com.unity.render-pipelines.high-definition-config": "file:../LocalPackages/com.unity.render-pipelines.high-definition-config",
+        "com.unity.render-pipelines.high-definition-config": "file:../../../com.unity.render-pipelines.high-definition-config",
         "com.unity.shadergraph": "file:../../../com.unity.shadergraph",
         "com.unity.test-framework": "1.1.14",
         "com.unity.test-framework.build": "0.0.1-preview.12",