Set DIALECT 2 as default configurable dialect version

[atakavci]

This change basically sets DIALECT 2 as the default dialect version on client side. Where DIALECT is relevant, each search/query will be using this default value unless it is configured otherwise.

Configuration could be changed explicitly at IDatabase level or at Query/AggregationRequest level.
A sample code showing how to change it using different constructs.

        // setting DIALECT at database level
        IDatabase db = ConnectionMultiplexer.Connect("localhost:6379").GetDatabase();
        SearchCommands ft = db.FT();
        ft.SetDefaultDialect(4);
        SearchResult result = ft.Search(index, new Query("@version:[123]"));

        // setting DIALECt at query level
        IDatabase db = ConnectionMultiplexer.Connect("localhost:6379").GetDatabase();
        ISearchCommands ft = db.FT();
        SearchResult result = ft.Search(index, new Query("@version:[123]").Dialect(4));

[uglide]

LGTM