Feature request: Support distinct option for de-duplication

### Description

Documentation: https://www.algolia.com/doc/guides/ranking/distinct/#distinct-for-de-duplication

I am hitting the 10kb limit for records and I need to be able to support de-duplication. Here is my use case:

- I have one model that contains a list of locations
- for some models, this list contains a lot of locations (some thousands)
- when indexing my model, I want to push 1 record for each location in the list: this will tremendously decrease record size while at the same time enhance the search experience

Are you willing to accept PRs for this feature? I can draft a spec here and get on with it 💪
Cheers!

Start by reading the linked Algolia distinct-for-de-duplication documentation and the existing indexing behavior in this Django integration. The issue names no files or tests, so the scope and entry point need to be established before implementation. Done should support one indexed record per location without exceeding the record-size limit, with tests covering the requested behavior.

Written by the indexing model from the issue text.