Remove pp submodule (#1770)

* Remove postprocessing submodule and use shipped package dependency.

.gitmodules

-[submodule "com.unity.postprocessing"]
-	path = com.unity.postprocessing
-	url = https://github.com/Unity-Technologies/PostProcessing.git
-	branch = v2

TestProjects/HDRP_Tests/Packages/manifest.json

 {
   "dependencies": {
-    "com.unity.postprocessing": "file:../../../com.unity.postprocessing",
     "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.shadergraph": "file:../../../com.unity.shadergraph",

TestProjects/LWGraphicsTest/Packages/manifest.json

 {
   "dependencies": {
-    "com.unity.postprocessing": "file:../../../com.unity.postprocessing",
     "com.unity.render-pipelines.core": "file:../../../com.unity.render-pipelines.core",
     "com.unity.render-pipelines.lightweight": "file:../../../com.unity.render-pipelines.lightweight",
     "com.unity.shadergraph": "file:../../../com.unity.shadergraph",

TestProjects/PostProcessing/Packages/manifest.json

 {
     "dependencies": {
-        "com.unity.postprocessing": "file:../../../com.unity.postprocessing",
+        "com.unity.postprocessing": "2.0.9-preview",
         "com.unity.testframework.graphics": "file:../../../com.unity.testframework.graphics",
         "com.unity.textmeshpro": "1.2.4"
     },

TestProjects/ShaderGraph/Packages/manifest.json

 {
   "dependencies": {
-    "com.unity.postprocessing": "file:../../../com.unity.postprocessing",
     "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.lightweight": "file:../../../com.unity.render-pipelines.lightweight",

build.py

         ("com.unity.render-pipelines.lightweight", os.path.join("com.unity.render-pipelines.lightweight")),
         ("com.unity.render-pipelines.high-definition", os.path.join("com.unity.render-pipelines.high-definition")),
         ("com.unity.shadergraph", os.path.join("com.unity.shadergraph")),
-        ("com.unity.postprocessing", os.path.join("com.unity.postprocessing")),
-        ("com.unity.testframework.graphics", os.path.join("com.unity.testframework.graphics")),
+        ("com.unity.testframework.graphics", os.path.join("com.unity.testframework.graphics"))
     ]
 
 def test_packages_list():
         "com.unity.render-pipelines.high-definition",
-        "com.unity.shadergraph",
-        "com.unity.postprocessing"
+        "com.unity.shadergraph"
     ]
 
 if __name__ == "__main__":

com.unity.render-pipelines.high-definition/package.json

     "unity": "2018.2",
     "displayName": "HD Render Pipeline",
     "dependencies": {
-        "com.unity.postprocessing": "2.0.10-preview",
+        "com.unity.postprocessing": "2.0.9-preview",
         "com.unity.render-pipelines.core": "3.0.1-preview",
         "com.unity.shadergraph": "3.0.1-preview"
     }

com.unity.render-pipelines.lightweight/package.json

     "unity": "2018.2",
     "displayName": "Lightweight Render Pipeline",
     "dependencies": {
-        "com.unity.postprocessing": "2.0.10-preview",
+        "com.unity.postprocessing": "2.0.9-preview",
         "com.unity.render-pipelines.core": "3.0.1-preview",
         "com.unity.shadergraph": "3.0.1-preview"
     }

com.unity.testframework.graphics/package.json

 {
 	"name": "com.unity.testframework.graphics",
 	"displayName":"Graphics Tests Framework",
-	"version": "0.1.1-preview",
+	"version": "3.0.1-preview",
 	"unity": "2018.2",
 	"description": "Provides test framework helpers for writing tests for graphics code, such as image comparison assertions and automatic management of reference images.",
 	"keywords": ["qa", "test", "testing", "tests", "graphics"],