tst_qlowenergycontroller to work without the specific device

Currently the BT LE tst_qlowenergycontroller relies on, for its live bluetooth part, on the presence of a very specific TI device with specific firmware version dating back to 2013. Having this specific device set up is practically a tricky requirement for a developer/tester to meet.

This task is about replacing this dependency with a more general Qt bluetooth counterpart.
The suggested approach is to:
1) analyze the autotest on what exactly it tests
2) move applicable parts to the manual tst_qlowenergycontroller_device (central) <=> bluetoothtestdevice test (peripheral)
3) remove the device specific parts from the test