Refactor the various operand/result/type iterators to use indexed_accessor_range.

This has several benefits:
* The implementation is much cleaner and more efficient.
* The ranges now have support for many useful operations: operator[], slice, drop_front, size, etc.
* Value ranges can now directly query a range for their types via 'getTypes()': e.g:
   void foo(Operation::operand_range operands) {
     auto operandTypes = operands.getTypes();
   }

PiperOrigin-RevId: 284834912