Include all *.aconfig files under aconfig directory

Forward fix for  https://googleplex-android-review.git.corp.google.com/c/platform/vendor/unbundled_google/packages/NexusLauncher/+/24579326/4/build.gradle

Bug: 294913042
Test: Local studio build
Flag: NA
Change-Id: Ib16469096c92eff4b50167e58fe5132e5467fdde