Abstract out node disposal (#1686)

* Abstract node disposal strategy

* Cleanup + lint

* Handle possibile scalesets being in resize state

* Setting the size is still exposed via CLI, we don't want to break that functionality

* PR comments

src/pytypes/onefuzztypes/enums.py

@@ -411,3 +411,7 @@ class UserFieldType(Enum):
     Str = "Str"
     DictStr = "DictStr"
     ListStr = "ListStr"
+
+
+class NodeDisaposalStrategy(Enum):
+    scale_in = "scale_in"