[SR-13699] Differentiation transform: support active enum values

[dan-zheng]

Previous ID	SR-13699
Radar	None
Original Reporter	@dan-zheng
Type	Sub-task

Additional Detail from JIRA

Votes	0
Component/s
Labels	Sub-task
Assignee	None
Priority	Medium

md5: 2a55bd2f0fb3d16f2f93210145515ac6

Parent-Task:

• SR-13695 Enum differentiation

Issue Description:

Differentiation transform needs to propagate adjoint values of enum associated values correctly. This is non-trivial because the switch_enum operand and successor block arguments have different types: the operand has an enum type but successor block arguments have associated values' type. Adjoint value propagation needs to construct enum adjoint value from associated values' adjoint values.