Migrate enum possible values to metadata

Summary:
Before this change, possible values for an enumeration were embedded within the attribute value itself.

After this change, possible values are located within the attribute metadata.

Reviewed By: LukeDefeo

Differential Revision: D41337003

fbshipit-source-id: cef5654a679e9b961e82993abb201b518fcbcd00

android/src/test/java/com/facebook/flipper/plugins/uidebugger/EnumMappingTest.kt

@@ -39,7 +39,6 @@ class EnumMappingTest {
   @Test
   fun testTurnsIntoEnumInspectable() {
     assertThat(
-        visibility.toInspectable(View.GONE),
-        equalTo(InspectableValue.Enum(Enumeration(setOf("VISIBLE", "INVISIBLE", "GONE"), "GONE"))))
+        visibility.toInspectable(View.GONE), equalTo(InspectableValue.Enum(Enumeration("GONE"))))
   }
 }