[Test] Check multipayload empty case wrapping.

Verify the behavior of swift_storeEnumTagMultiPayload in the face of
small payload sizes (8 bits) and many empty cases (more than 2^8).

Additional test of the behavior that was fixed at
swiftlang#42131

Author: nate-chandler

validation-test/Runtime/Inputs/enum-multipayload-emptycase-storetag_Resilient.swift

@@ -0,0 +1,3 @@
+public struct Bewl {
+  var value: Bool
+}