Isolate Shared Test Code (#252)

The goal of this make sure that test code is correctly organized to ensure that test suites aren't dependent on each other.
* UnitTests get their own project now (renaming Microsoft.SqlTools.ServiceLayer.Test to Microsoft.SqlTools.ServiceLayer.UnitTests) which is about 90% of the changes to the files.
* IntegrationTests no longer depends on UnitTests, only Test.Common
* Any shared components from TestObjects that spins up a "live" connection has been moved to IntegrationTests Utility/LiveConnectionHelper.cs
* The dictionary-based mock file stream factory has been moved to Test.Common since it is used by UnitTests and IntegrationTests
    * Added a overload that doesn't take a dictionary for when we don't care about monitoring the storage (about 90% of the time)
* The RunIf* wrapper methods have been moved to Test.Common
* OwnerUri and StandardQuery constants have been moved to Test.Common Constants file

* Updating to latest SDK version available at https://www.microsoft.com/net/core#windowscmd

* Moving unit tests to unit test folder

* Changing namespaces to UnitTests

* Moving some constants and shared functionality into common project, making the UnitTests reference it

* Unit tests are working!

* Integration tests are working

* Updating automated test runs

* Fixing one last broken unit test

* Exposing internals for other projects

* Moving edit data tests to UnitTest project

* Applying refactor fixes to unit tests

* Fixing flaky test that wasn't awaiting completion

test/Microsoft.SqlTools.ServiceLayer.IntegrationTests/project.json

@@ -33,7 +33,7 @@
       "target": "project"
     },
     "Moq": "4.6.36-alpha",
-    "Microsoft.SqlTools.ServiceLayer.Test": "1.0.0-*"
+    "Microsoft.SqlTools.ServiceLayer.Test.Common": "1.0.0-*"
   },
   "testRunner": "xunit",
   "frameworks": {