fix: Reset project version to 2019.3.0f1 and remove all related changes (+1 squashed commits)

[817e4ec] fix(build): Replace zenject.ref.asmref with Zenject.SampledBuilder.Editor.asmdef which is only included in the editor to avoid usage of UnityEditor outside of the editor (+1 squashed commits)
[8f9dafb] fix(.gitignore): Ignore UnityProject/UserSettings/* which is a new user specific folder, which previously was stored in /Library (see https://forum.unity.com/threads/whats-the-usersettings-directory.754436/#post-5029937)
fix(packages-lock.json): Should be checked in, but wasn't or did not exist in the old unity version (+1 squashed commits)
[1f431e3] fix(161): Update zenject.asmdef to specify all default values

Author: kstreicher

.gitignore

@@ -18,3 +18,4 @@ project_root_marker
 
 # Added by Mathijs:
 .DS_Store
+UnityProject/UserSettings/

UnityProject/Assets/SampleBuilder/Editor/Zenject.SampleBuilder.Editor.asmdef

@@ -0,0 +1,17 @@
+{
+    "name": "Zenject.SampleBuilder.Editor",
+    "references": [
+        "GUID:0d8beb7f090555447a6cf5ce9e54dbb4"
+    ],
+    "includePlatforms": [
+        "Editor"
+    ],
+    "excludePlatforms": [],
+    "allowUnsafeCode": false,
+    "overrideReferences": true,
+    "precompiledReferences": [],
+    "autoReferenced": false,
+    "defineConstraints": [],
+    "versionDefines": [],
+    "noEngineReferences": false
+}