Support error return and out parameters in define_class!

[madsmtm]

Add the equivalent of #276 and #277 to define_class!.

Effectively the implementation is:

// Result<(), Retained<NSError>> -> Bool
match res {
    Ok(()) => Bool::YES,
    Err(err) => {
        // Intentionally not objc_autoreleaseReturnValue, since the optimization that enables will not be able to kick in
        *__err_param = objc_autorelease(err);
        Bool::NO
    },
}

// Result<Retained<T, O>, Retained<NSError>> -> *mut T
match res {
    Ok(obj) => obj.release_according_to_memory_management_rules(sel), // See #282
    Err(err) => {
        // Intentionally not objc_autoreleaseReturnValue
        *__err_param = objc_autorelease(err);
        ptr::null_mut()
    },
}

See #277 (comment) for further ABI details.

[madsmtm]

So to be clear, in the intermediate, users must handle this themselves using something like:

// Returning boolean
#[unsafe(method(myMethodWithError:))]
fn my_method_with_error(&self, err_param: Option<&mut *mut NSError>) -> bool {
    let res: Result<(), Retained<NSError>> = todo!();

    match res {
        Ok(()) => true,
        Err(err) => {
            if let Some(err_param) = err_param {
                *err_param = Retained::autorelease_ptr(err);
            }
            false
        },
    }
}

// Returning `Retained` object
#[unsafe(method_id(myMethodWithError:))]
fn my_method_with_error(&self, err: Option<&mut *mut NSError>) -> Option<Retained<Self>> {
    let res: Result<Retained<Self>, Retained<NSError>> = todo!();

    match res {
        Ok(value) => Some(value),
        Err(err) => {
            if let Some(err_param) = err_param {
                *err_param = Retained::autorelease_ptr(err);
            }
            None
        },
    }
}