Add a binary path param to update_binary_command().

This allows writing native tests for non-A/B update_binary_command().
Prior to this CL, it was extracting the updater to a hard-coded
location (/tmp/update_binary) that's not available under the test
environment.

Test: recovery_component_test on angler and marlin respectively.
Test: Sideload OTA packages on angler and marlin respectively.
Change-Id: I78b9cc211d90c0a16a84e94e339b65759300e2a8