* MO update for MaxPool-8
* using attrs in op constructor
* remove pads_value attr and pad fusing
* added axis and index_element_type parameters
* updated mo maxpool-8
* added maxpool-8->maxpool-1 transformation, disabled Pad to MaxPool fusing
* added remove_values_output to pooling extractors
* moved remove_values_output attribute to pooling infer function
* fixed ir_comparator tests
* disabled pad to maxpool fusing test
* added downgrade transformation test
* downgrade transformation update
* updated ir reader and tf pooling layer tests
* updated onnx pooling layer tests and MO infer unit test
* updated ir reader extender
* uncommented layer tests code
* disabled MaxPool-8 python binding test
* comment resolving, removed PadMaxPool fusing
* removed test
* downgrade transformation fix, MO codestyle changes
* removed axis check from downgrade transformation
* mark max_pool_test as xfail
* updated downgrade transformation test
* using OPENVINO_RTTI
