* Add visitor and backend tests.
* Add reduction_axes to SLTs, serialization and backend tests.
* Update backend tests.
* Move backend tests to template plugin, remove old ones.
* Apply correct format.
* Add BF16 to SLT, add comment regarding deprecated class.
* Remove BF16 precision as it is not supported in windows, no default values for attributes.
* Reuse Tensor from base_reference_test.hpp
Szymon Durawa