tests: Add the missing tests in applypatch_modes_test.cpp.

This file was somehow missed when converting from Android.mk to
Android.bp. This CL addresses the issue by picking up all the .cpp files
in the test source dir.

Test: Run recovery_{unit,component}_test on marlin. Check the reported
      number of tests (94 for unit test and 157 for component test).
Change-Id: I50435b07fcb8602ef7b3f7e7d3a69e10b6a5932d