Import Android SDK Platform P [4456821]

/google/data/ro/projects/android/fetch_artifact \
    --bid 4456821 \
    --target sdk_phone_armv7-win_sdk \
    sdk-repo-linux-sources-4456821.zip

AndroidVersion.ApiLevel has been modified to appear as 28

Change-Id: I2d206b200d7952f899a5d1647ab532638cc8dd43