Export framework turbine stubs as android_stubs_private

Collect the private framework APIs that are used to compile platform
apps like SystemUI into an android_private_stubs jar.  This should
be sufficient to give to Android Studio to enable platform app
development.

Also produce android_stubs_private_framework_aidl, which is an
imperfect framework.aidl file that still needs manual modification
before it is suitable for use in studio (b/259594098).

Test: m sdk dist
Bug: 251871740
Change-Id: Ia517a90e93540454e02fa9e0930e0a13893c9fff