* Safe loading of default plugins
1. In case of default plugins.xml all plugins is registered by
absolute paths
2. In case of user API user is able to specify abs or rel path
or plugin name to be found in ENV
3. Update `ov::util::get_absolute_file_path()` in order to prevent
checking file exists or can be accessed
4. Add tests + delete duplicated tests
* Add `OV_CORE_CALL_STATEMENT` to `Core()` ctor
to convert InferenceEngine::Exception to
ov::Exception
* Add `ie_plugins.hpp` dependency to `ov_infer_unit_tests`
* Update C and Py docstrings
* Comment fix
* Update LD_LIB_PATH in openvino-onnx/Dockerfile
* Skip `test_register_plugin*` for Debian job
54ea2612ae