1. Using of the "Closed" flag was unified:
a) this flag is applicable for TopoDS_Wire and TopoDS_Shell only, because these entities may hedge an area in 2D space or a volume in 3D space correspondingly;
b) other types of TopoDS shapes are passing over this flag;
c) changing of this flag should be controlled by high-level algorithms (not BRep_Builder).
2. Implemented verification of the closedness of edges. An edge is closed if and only if its first and last vertices are the same.
3. Test cases were changed according to new behavior.
Method BRep_Tool::IsClosed() extended to analyze closure of wires in addition to shells and solids.
External and Internal edges and vertices are ignored in this check.
Analysis of compounds is disabled.
Update of flag Closed according to actual state is added in most places where new shells are constructed.
Draw-command and test case for issue CR25202
