### 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
readerContext = new ReaderContext(id, indexService, shard, reader, keepAliveInMillis, true);
            }
            reader = null;
            final ReaderContext finalReaderContext = readerContext;
            final SearchOperationListener searchOperationListener = shard.getSearchOperationListener();
            searchOperationListener.onNewReaderContext(finalReaderContext);
            if (finalReaderContext.scrollContext() != null) {
                searchOperationListener.onNewScrollContext(finalReaderContext);
            }
            readerContext.addOnClose(() -> {
                try {
                    if (finalReaderContext.scrollContext() != null) {
                        searchOperationListener.onFreeScrollContext(finalReaderContext);
                    }
                } finally {
                    searchOperationListener.onFreeReaderContext(finalReaderContext);
                }
            });
            putReaderContext(finalReaderContext);
            readerContext = null;
            return finalReaderContext;
        } finally {
            Releasables.close(reader, readerContext, decreaseScrollContexts);
        }
    }
    /**
     * Opens the reader context for given shardId. The newly opened reader context will be keep
     * until the {@code keepAlive} elapsed unless it is manually released.
     */
    public void openReaderContext(ShardId shardId, TimeValue keepAlive, ActionListener<ShardSearchContextId> listener) {