* [MO] Add support to moc_frontend of ":" as delimiter for --input
Additions:
Changed default logic for 'Place::get_in(out)put_port' to return nullptr
Changed default logic for 'InputModel::get_place_by_tensor(operation)_name' to return nullptr
* Corrected comments in code
* Missing empty line
* Clang format fixes
* Fix review comments
* Updated test to verify review comments fixes
* Update unit tests after rebase
* Apply review comments