Extend inheritance support for multiple levels

[aalramadan]

Currently, the tool's inheritance functionality is limited to single-level inheritance. It does not consider scenarios where the base class may itself inherit from another base class (i.e., multilevel inheritance).

For example, if class A inherits from class B and class B inherits from class C, then when stereotyping class A, only the non-private attributes of class B are considered in class A.

Ideally, it should also consider the non-private attributes of class C.

[aalramadan]

Support for multi-level inheritance is added.