Enables support for transforming loops of the form
for (auto I = Cont.rbegin(), E = Cont.rend(); I != E;++I)
This is done automatically in C++20 mode using std::ranges::reverse_view but there are options to specify a different function to reverse iterator over a container.
This is the first step, down the line I'd like to possibly extend this support for array based loops
for (unsigned I = Arr.size() - 1;I >=0;--I) Arr[I]...
Currently if you pass a reversing function with no header in the options it will just assume that the function exists, however as we have the ASTContext it may be as wise to check before applying, or at least lower the confidence level if we can't find it.