v4: move apf_interpreter.{h,c} into v4 subdirectory am: 6d5cbf6243

Original change: https://android-review.googlesource.com/c/platform/hardware/google/apf/+/3029876

Change-Id: I93944457262e376daa3a3c81db85f4cb5166c7b7
Signed-off-by: Automerger Merge Worker <[email protected]>