* Fix missed/redundant attrs for some operations
* Align auto_pad attr values in spec
* Update MO IR Reader extenders for appropriate operations
* Allign auto_pad attr values for appropriate operations
* Remove changes in extenders
* Update backend_attrs for some operations
* Changes in shape_infer functions to correct work with explicit mode
* Apply offline comments
* Remove unnnecessary ir_version checks in the MO
* Cleaned up 'backend_attrs_v2' function
* Small clean up from the 'TFCustomSubgraphCall'
* Clean up the MO extractor attributes mapping
* Renamed PreluOp to PReLU
* Removed back phase transformations related to IRv7
* Fixed setting value for the input port using the 'set_value' method
* Removed front and middle phase transformations related to IRv7
* Cleanup the rest of the Model Optimizer transformations from IRv7 specific transformations
* Final cleanup of the deprecated IR v7 related code
* Removed 'blobs_as_input' usage in the Model Optimizer.
* Removed function '_fuse_add' from the Model Optimizer since it is not used anymore.
* Removed 'keep_in_IR' node attribute for FakeQuantize ops in the MO
* Disabled failing gpu_engine.user_context test
Ivan Tikhonov