Update Ethiopic fonts to a variable format

Bug: 169374341

Test: All tests below are manual.
Test: 0. Open a reference device with an existing set of fonts
Test: 1. Upload new fonts.xml and the new fonts to a test device
Test: 2. Change language to Ethiopic on both devices
Test: 3. Open settings on both devices and visually compare them (they
should be the same)
Test: 4. Open the following pages on the test device (and on a reference
device):
Test:  https://en.wikipedia.org/wiki/Ethiopic_(Unicode_block)
Test:  https://unicode.org/udhr/d/udhr_amh.html
Test:  https://www.wordproject.org/bibles/verses/amharic/26_peace.htm
Test:  ... and visually compare them (they should be the same)

Change-Id: I12488fb505ae7b3c506383c7cec7cdebe133994d