Method GetGroupedWindowSqlPreviewAsync(long, IEnumerable<GroupFieldRequest>, IEnumerable<AggregateRequest>, IEnumerable<WindowFuncRequest>, IEnumerable<WindowFieldRequest>, IEnumerable<WindowOrderRequest>, string?)

SQL preview for GroupBy + Window query.
Base implementation returns placeholder (overridden in Pro).

public override Task<string> GetGroupedWindowSqlPreviewAsync(long schemeId, IEnumerable<GroupFieldRequest> groupFields, IEnumerable<AggregateRequest> aggregations, IEnumerable<WindowFuncRequest> windowFuncs, IEnumerable<WindowFieldRequest> partitionBy, IEnumerable<WindowOrderRequest> orderBy, string? filterJson = null)