Handle explicit cast of union member (#210)

Union members are translated using accessors:

```cpp
union u { int a; }
*(char *)&u.a = 0xFF;
```
becomes

```rs
struct u { __bytes: Value<Box<[u8]>> }
impl u { pub fn a() -> Ptr<i32> { ... } } // the accessor

u.a().reinterpret_cast<u8>().write(0xFF) // Before this PR it did not compile: (u.a() as Ptr<u8>).write(0xFF)
```

This PR replaces the wrong `(u.a() as Ptr<u8>)` pattern with
`u.a().reinterpret_cast<u8>()`

Author: lucic71

cpp2rust/converter/models/converter_refcount.cpp

@@ -1313,9 +1313,9 @@ bool ConverterRefCount::VisitExplicitCastExpr(clang::ExplicitCastExpr *expr) {
     } else if (expr->getSubExpr()->getType()->isPointerType() &&
                !expr->getSubExpr()->isNullPointerConstant(
                    ctx_, clang::Expr::NPC_ValueDependentIsNull)) {
-      StrCat(std::format("({}.to_strong().as_pointer() as {})",
+      StrCat(std::format("{}.reinterpret_cast::<{}>()",
                          ToString(expr->getSubExpr()),
-                         ToString(expr->getType())));
+                         ConvertPointeeType(expr->getType())));
       return false;
     }
     return Converter::VisitExplicitCastExpr(expr);