Convert android.mk to android.bp

In order to o speedup the development cycle, transform android.mk to
android.bp

* add license
* add AndroidTest.xml

Change-Id: I970a37e967d41abd38951cc8a5598eb1e0b27c3d
Fixes: 117861161
Test: atest DownloadProviderTests DownloadPublicApiAccessTests \
    DownloadProviderPermissionTests
12 files changed