Implement aidl_library module type

We currently specifies aidl files directly to the srcs prop on a filegroup or other module types such as cc_library or java_library. We use aidl.include_dirs prop to specify paths to aidl headers. This include_dirs pattern isn't migratable to Bazel because Bazel requires explicit dependencies.

This CL introduces aidl_library to better map with Bazel's aidl_library rule and to enable aidl headers to be specified in a separate aidl_library or the hdrs prop. A follow-up CL will turn on inputs sandbox to enforce all aidl headers be explicitly specified in Android.bp

Test: go test
Bug: 278704136
Change-Id: I2c99af080525bf8a6c5724ed5ee2001842969098