swift

76ad4abd - [AutoDiff upstream] Fill in derivative witness table/vtable thunks. (#30634)

[AutoDiff upstream] Fill in derivative witness table/vtable thunks. (#30634) Generate `differentiable_function` and `differentiable_function_extract` in derivative witness table/vtable thunks. `differentiation_function` is later canonicalized by the differentiation transform. Add SIL FileCheck tests.