UT-109: move to embedded package without tests, plus tests in assets folder

This is from a discussion on #devs-packman:
- Work on your package in the Packages directory.
- Put tests in the github repo, not in the package itself.

Author: Benoit Hudson

Assets/com.unity.formats.fbx/EditorTests.meta renamed to Assets/com.unity.formats.fbx.tests.meta

@@ -15,7 +15,7 @@ public abstract class ExporterTestBase
         /// Use this path if you want to load some data for testing, e.g. a
         /// material or scene or fbx.
         /// </summary>
-        public const string PathToTestData = "Assets/com.unity.formats.fbx/EditorTests";
+        public const string PathToTestData = "Assets/com.unity.formats.fbx.tests";
 
         bool isAutoUpdaterOn;
         /// <summary>