AndroidTestRunner: allow to call additional/extra adb call

Add an option to AndroidTestRunner to call additional adb commands before running the test.
Those commands could be set to the test target with CMake.

An example of such a need can be found in QtMultimedia - in qtscreencapturebackend test.

ScreenCapture feature needs an acceptation of Security Popup. It can be automatically accepted with adb command:

"adb shell appops set org.qtproject.example.tst_qscreencapturebackend PROJECT_MEDIA allow"

But currently there is no way to call it by androidtestrunner after installation and before running the test