Update document query for v0.28.0

[bidoubiwa]

For consistency between all routes that provide query parameters, this PR add a structure DocumentQuery in which you can set the fields parameters.

Changes

• New method index.get_document_with gives the possibility to fetch documents with

Usage

    let mut document_query = DocumentQuery::new(&index);
    document_query.with_fields(["id"]);
    
    let document = index.get_document_with::<MyObjectReduced>("1", &document_query).await.unwrap();