Merge "Switch aidl::nullable to std::optional" into rvc-dev-plus-aosp am: ce3fd2b509 am: 668e478fda am: 4f1dc6586e

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/12325559

Change-Id: I511d18643f189932cb1a4e5793de456893c151aa