Add `get_int_max_str_digits` and `set_int_max_str_digits` in `sys`.

## Feature

These were newly added in 3.11 and should be relatively straightforward to add, reference: https://docs.python.org/3/library/stdtypes.html#int-max-str-digits

Additions to `int_info` already exist so just the get/set function should be added. (See `PyIntInfo` in [`sys.rs`](https://github.com/RustPython/RustPython/blob/main/vm/src/stdlib/sys.rs)).
