Add ExemptAidlInterfacesGenerator for PermissionAnnotationDetector

This CL is a prerequisite for migrating PermissionAnnotationDetector to
a global lint check. This will enforce newly added system services to
use @EnforcePermission annotations.

To determine the newly added system services, the global lint check will
use a pre-computed set of existing, i.e. exempt, AIDL interfaces in
AOSP. To compute the set, the CL introduces the following:
* ExemptAidlInterfacesGenerator, the Android Lint check that creates a
  set of AIDL Interfaces for a build target.
* generate-exempt-aidl-interfaces.sh, a Bash script that runs the lint
  check on the entire source tree and aggregates the results.

Bug: 363248121
Test: ExemptAidlInterfacesGeneratorTest
Flag: EXEMPT lint check
Change-Id: Id700fb74485e63c76bbdb163079dd90b08c100dc