### 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
checkKeepAliveLimit(keepAlive.millis());
        final IndexService indexService = indicesService.indexServiceSafe(shardId.getIndex());
        final IndexShard shard = indexService.getShard(shardId.id());
        final SearchOperationListener searchOperationListener = shard.getSearchOperationListener();
        shard.awaitShardSearchActive(ignored -> {
            Engine.SearcherSupplier searcherSupplier = null;
            ReaderContext readerContext = null;
            try {
                searcherSupplier = shard.acquireSearcherSupplier();
                final ShardSearchContextId id = new ShardSearchContextId(
                    sessionId,
                    idGenerator.incrementAndGet(),
                    searcherSupplier.getSearcherId()
                );
                readerContext = new ReaderContext(id, indexService, shard, searcherSupplier, keepAlive.millis(), false);
                final ReaderContext finalReaderContext = readerContext;
                searcherSupplier = null; 
                searchOperationListener.onNewReaderContext(readerContext);
                readerContext.addOnClose(() -> searchOperationListener.onFreeReaderContext(finalReaderContext));
                putReaderContext(readerContext);
                readerContext = null;
                listener.onResponse(finalReaderContext.id());
            } catch (Exception exc) {
                Releasables.closeWhileHandlingException(searcherSupplier, readerContext);
                listener.onFailure(exc);
            }
        });
    }
    protected SearchContext createContext(
        ReaderContext readerContext,