OpenAPI: Create overloaded constructors for PathEntity

Create overloaded constructors for PathEntity. Now we are using a lot of nulls when constructing PathEntity instances. In fact, we have three scenarios:

• entity for config path which allows full CRUD

• entity for action/RPC which has POST only

• entity for operational dattastore which has GET only

Create creating overloaded constructor to simplify PathEntity instantiation in these scenarios.