Added/refined log messages for ANGLE usage/settings.

There are now log messages for whether or not we're using ANGLE, and
if so, which backend Vulkan and Skia are using.

Test: Run an application and look at logcat output
Change-Id: I6f97b1b6786ec7d6a2f7ce14c61b108b0b711a11
(cherry picked from commit 7bf58d89966fba02f39062d273faba25f4af42b0)