[BUG] Heap analyses should react to type conversions and castings

[lucaneg]

Description Sometimes, to explicitly invoke a method from a superclass (e.g., super.foo()), the receiver of the call can be set to (Superclass) this, that is, the current object casted to its supertype. Logic inside heap abstractions should support expressions of this kind: e.g., at https://github.com/lisa-analyzer/lisa/blob/0be57d8e989e15f576a1f78d795b278128ea5298/lisa/lisa-analyses/src/main/java/it/unive/lisa/analysis/heap/pointbased/AllocationSiteBasedAnalysis.java#L126 rhs might be a BinaryExpression with a TypeConv operator.