### Description

We now support storing KNN vectors as part of our indexed data.  These vectors should be included in the disk usage API.
server/src/main/java/org/elasticsearch/action/admin/indices/diskusage/IndexDiskUsageStats.java
builder.field(STORE_SIZE, new ByteSizeValue(indexSizeInBytes));
        builder.field(STORE_SIZE_IN_BYTES, indexSizeInBytes);
        
        builder.startObject("all_fields");
        total.toXContent(builder, params);
        builder.endObject();
        
        builder.startObject("fields");
        {
            final List<Map.Entry<String, PerFieldDiskUsage>> entries = fields.entrySet()
                .stream()
                .sorted(Map.Entry.comparingByKey())
                .toList();
            for (Map.Entry<String, PerFieldDiskUsage> entry : entries) {
                builder.startObject(entry.getKey());
                entry.getValue().toXContent(builder, params);
                builder.endObject();
            }
        }
        builder.endObject();
        return builder;
    }
    @Override
    public String toString() {
        return Strings.toString(this);
    }
    /**
     * Disk usage stats for a single field
     */
    public static final class PerFieldDiskUsage implements ToXContentFragment, Writeable {