pdpd Place: remaining methods, refactoring, unit tests (#6637)
* pdpd Place: remaining methods, refactoring, unit tests
* resolve merge issues
* use references instead of shared_ptr for Var and Op descs
* Add import pdpd fuzz test; To enable collection of pdpd models, cmake NGRAPH_PDPD_FRONTEND_ENABLE key should be set, the models will be generated to pdpd_test_models folder.
* fix ngraph codestyle
* fix review comments
* Add new methods for Place class
* fix implementation, add tests
* Place: Return nullptr instead of throwing an exception
* ngraph codestyle
* revert return nullptr
* fix build
* fix tests
* fix fuzzing tests
* fix fuzzing tests
* fix readme file
* Revert "fix readme file"
This reverts commit d061e69a0d.
* Resolve review comments
* ngraph codestyle
Co-authored-by: Somsikov, Andrey <andrey.somsikov@intel.com>
6e8b0e0ea6