Add empty system and module-lib APIs for i18n

These are needed for backwards compatibility checks in i18n when
adding system and module-lib API surfaces.

Bug: 216435117
Test: m i18n-module-sdk
      - Verify the snapshot includes system and module-lib API files.
      - Without these changes the build fails with missing filegroups.
Change-Id: I4383739f8642943f50e6ad68ffcd8fe90426db56
4 files changed