Store the arguments of CXXConstructExpr in a trailing array. This is very similar to the
CallExpr case in D55771, with the exception that there is only one derived class
(CXXTemporaryObjectExpr) and that we compute the offset to the trailing array instead
of storing it.
This saves one pointer per CXXConstructExpr and CXXTemporaryObjectExpr.
(with some comments inline)