Fix warnings in project.json

PR #2493 introduced the new project.json schema. The tree has 118 files
with the old schema, which added several hundred warnings.

This change can't go in until PR #2864 does - it relies on those bug
fixes.

test/dotnet-compile.UnitTests/project.json

@@ -1,7 +1,12 @@
 {
   "version": "1.0.0-*",
-  "compilationOptions": {
-    "keyFile": "../../tools/Key.snk"
+  "buildOptions": {
+    "keyFile": "../../tools/Key.snk",
+    "copyToOutput": {
+      "include": [
+        "../../TestAssets/TestProjects/TestAppWithLibrary/**/*"
+      ]
+    }
   },
   "dependencies": {
     "Microsoft.NETCore.App": {
@@ -38,8 +43,10 @@
       ]
     }
   },
-  "content": [
-    "../../TestAssets/TestProjects/TestAppWithLibrary/**/*"
-  ],
-  "testRunner": "xunit"
-}
+  "testRunner": "xunit",
+  "publishOptions": {
+    "include": [
+      "../../TestAssets/TestProjects/TestAppWithLibrary/**/*"
+    ]
+  }
+}