OsuLogin: Generate AOSP keys and sign APK

Generate keys for the OsuLogin APK and
sign the APK using those keys.

Note that these keys are only used to sign locally-built APKs
during development. They are not release keys.

Bug: 149589553
Test: compiles
Change-Id: I6abee1618faba127dbe0c1618071985a166f6927
4 files changed