Move unused forked code to external directory (#1192)

* Move unused forked code to external directory

* Fix SLN build errors

* Add back resource provider core since it's referenced by main resource provider project

* Update PackageProjects step of pipeline

build.json

@@ -25,9 +25,6 @@
     "Microsoft.SqlTools.ServiceLayer"
   ],
   "PackageProjects": [
-    "Microsoft.SqlTools.CoreServices",
+    "Microsoft.SqlTools.Hosting"
-    "Microsoft.SqlTools.DataProtocol.Contracts",
-    "Microsoft.SqlTools.Hosting.Contracts",
-    "Microsoft.SqlTools.Hosting.v2"
   ]
 }