Add nGraph function serialization. (#2579)

Add nGraph function serialization. (#2579)

* Add nGraph function serialization.

* Turn of execption throwing on failed visitation.

* CNNNetworkNgrapImpl serialize also support fallback to v7 serialization.

* Add error message for legacy IR not implemented case.

* Store tests models in files.

* Add tests with multiple layers.

* Style aligned to IE rules.

* Add visit_attributes to ExecutionNode.

* Layer version XML atribute implementation.

* Fix opset atribute creation for ExecutionGraph. Refactoring.

* Add missing header.

* Move opset collecting to private scope.

* Add missing header.

* Add test wit multiple oututs. Fix found issues: constant name, result
outputs.

* Move serialization to transformation library.

* Add versioning to serialization transformation.

* Add functional tests with ONNX importer path.

* Add nodes unique name checking and correction.

* Add checks for unsuported cases: dynamic shapes & GenericIE node

* General refactoring.

* Add comment describing type name translations.

* Add serialization deterministicity tests.

It's needed to ensure that subsequent calls to serialize() on the same function are giving the same results.

* Serialization in CNNNetworkNGraphImpl::serialize executed via pass::Manager.

Co-authored-by: Gleb Kazantaev <gleb.nnstu@gmail.com>
* NGRAPH_CHECK messages refactored.

* Performance and const correctness refactoring.

* Style formatting applied.

* Code simplifaction.

* Serialize transformation documentation refactoring.

* Changed compare_function() to throw on functions with multiple outputs.

Before this check was implemented with assert which means it was working
only in debug builds. Now it is working also in release build.

* Adjust tests to new compare_functions() behaviour.

* Replace cmakes add_definitions with more modern target_compile_definitions

Co-authored-by: Gleb Kazantaev <gleb.nnstu@gmail.com>