[analyzer] Pass correct bldrCtx to computeObjectUnderConstruction

In case when the prvalue is returned from the function (kind is one
of `SimpleReturnedValueKind`, `CXX17ElidedCopyReturnedValueKind`),
then it construction happens in context of the caller.
We pass `BldrCtx` explicitly, as `currBldrCtx` will always refer to callee
context.

In the following example:
```
struct Result {int value; };
Result create() { return Result{10}; }
int accessValue(Result r) { return r.value; }

void test() {
   for (int i = 0; i < 2; ++i)
      accessValue(create());
}
```

In case when the returned object was constructed directly into the
argument to a function call `accessValue(create())`, this led to
inappropriate value of `blockCount` being used to locate parameter region,
and as a consequence resulting object (from `create()`) was constructed
into a different region, that was later read by inlined invocation of
outer function (`accessValue`).
This manifests itself only in case when calling block is visited more
than once (loop in above example), as otherwise there is no difference
in `blockCount` value between callee and caller context.
This happens only in case when copy elision is disabled (before C++17).

Reviewed By: NoQ

Differential Revision: https://reviews.llvm.org/D132030