### Description

In [siren federate](https://siren.io/federate/) we extend the `SearchService` to create `SearchContext` instances. In 8.8 this is not possible anymore because the `createContext` method takes the `ResultsType` enum which is package private.

https://github.com/elastic/elasticsearch/blob/b640c217cccab67dce7d954bc92b6b519c102b16/server/src/main/java/org/elasticsearch/search/SearchService.java#L992-L998

In order to be able to keep on calling that method from another package, the visibility of the enum `ResultsType` should be increased to `protected`.
server/src/main/java/org/elasticsearch/search/SearchService.java
}
        return reader;
    }
    final ReaderContext createOrGetReaderContext(ShardSearchRequest request) {
        if (request.readerId() != null) {
            try {
                return findReaderContext(request.readerId(), request);
            } catch (SearchContextMissingException e) {
                final String searcherId = request.readerId().getSearcherId();
                if (searcherId == null) {
                    throw e;
                }
                final IndexService indexService = indicesService.indexServiceSafe(request.shardId().getIndex());
                final IndexShard shard = indexService.getShard(request.shardId().id());
                final Engine.SearcherSupplier searcherSupplier = shard.acquireSearcherSupplier();
                if (searcherId.equals(searcherSupplier.getSearcherId()) == false) {
                    searcherSupplier.close();
                    throw e;
                }
                return createAndPutReaderContext(request, indexService, shard, searcherSupplier, defaultKeepAlive);
            }
        } else {
            final long keepAliveInMillis = getKeepAlive(request);
            final IndexService indexService = indicesService.indexServiceSafe(request.shardId().getIndex());
            final IndexShard shard = indexService.getShard(request.shardId().id());
            final Engine.SearcherSupplier searcherSupplier = shard.acquireSearcherSupplier();
            return createAndPutReaderContext(request, indexService, shard, searcherSupplier, keepAliveInMillis);
        }
    }
    final ReaderContext createAndPutReaderContext(