Add a new option in recovery menu to test the background texts

Add a new option "Run locale test" to check the background text
images (i.e. texts for "erasing", "error", "no_command" and "installing"
with different locales.)

Use volume up/down button to cycle through all the locales embedded in
the png file, and power button to go back to recovery main menu.

Test: Run locale test with bullhead.
Change-Id: Ib16e119f372110cdb5e611ef497b0f9b9b418f51