Provide a way to set a default fetch mode

### Code of Conduct

- [x] I agree to follow Django's Code of Conduct

### Feature Description

Provide something (a setting?) to allow setting the default fetch mode to something other than `FETCH_ONE`.

### Problem

I would really like to have `FETCH_PEERS` as the default fetch mode, and perhaps some people like to have `FETCH_RAISE`, I dunno.

At the moment if you want to have this behaviour you need to have something like a base manager or queryset that everything else inherits from, which is a lot of boilerplate.

### Request or proposal

request

### Additional Details

_No response_

### Implementation Suggestions

_No response_

No files or tests are named. Start by reviewing the existing handling of FETCH_ONE, FETCH_PEERS, and FETCH_RAISE, including how a base manager or queryset currently supplies defaults. Done means a documented setting or API can change the default fetch mode without repeated boilerplate.

Written by the indexing model from the issue text.