Add Bulgarian Phonetic keyboard layout support

Add keyboard layout support for entering Bulgarian text. This will be used
for connecting a physical keyboard and typing in Bulgarian.

Bug: 141126644
Test: connect USB/Bluetooth keyboard and choose "Bulgarian Phonetic" keyboard
layout, start typing in a input window.

Change-Id: Ifbbb5e6927272cea90bf7083ad120daead22e77b
3 files changed