This prepares for moving more codes from recovery into librecovery, so
that they will become more easily testable. recovery_main.cpp will be
the source code for recovery module, with the rest moved into
librecovery. recovery_main.cpp mainly does the initializations, such as
setting up the logger.
Test: mmma -j bootable/recovery
Test: recovery_component_test
Test: Build and boot into recovery image on marlin.
Change-Id: I8e846524546b6f3f0e32ed869e851f62261eef23
Merged-In: I8e846524546b6f3f0e32ed869e851f62261eef23
6d99d4b457