Move definition of Flags

This makes the ordering of definitions and match branches more consistent.

Author: esoterra

design/mvp/canonical-abi/definitions.py

@@ -128,10 +128,6 @@ class Record(ValType):
 class Tuple(ValType):
   ts: [ValType]
 
-@dataclass
-class Flags(ValType):
-  labels: [str]
-
 @dataclass
 class Case:
   label: str
@@ -159,6 +155,10 @@ class Result(ValType):
   ok: Optional[ValType]
   error: Optional[ValType]
 
+@dataclass
+class Flags(ValType):
+  labels: [str]
+
 @dataclass
 class ResourceType(Type):
   dtor: Optional[Callable[[int],None]]