Downloadable Font sample.

This sample demonstrates how to request to download a font:
- From Java code
- By declarating it in the XML in advance of the usage

This sample uses a GmsCore as the font pvovider, to run the sample app,
the device needs to install at least V11 of GmsCore.

Test: Manual

Change-Id: I3c3a10f08d4f65f943eea8cf406a20d89d1318df