Supports downloading and generating future universe files

Expected Behavior

LEAN should provide a generic data downloader wrapper that:

• Supports downloading historical market data from multiple data sources via their respective historical providers
• Supports downloading universe files (Future)

Actual Behavior

Each data source currently implements its own DataDownloader with:

• Duplicated logic for request handling, retries, pagination, file output, and error handling
  For example, PolygonDataDownloader explicitly implements this logic instead of reusing a shared abstraction:
  https://github.com/QuantConnect/Lean.DataSource.Polygon/blob/master/QuantConnect.Polygon/PolygonDataDownloader.cs

Potential Solution

Introduce a Generic DataDownloader wrapper / base implementation that:

• Encapsulates shared downloader logic

Example for Brokerages: https://github.com/QuantConnect/Lean/blob/master/DownloaderDataProvider/Models/BrokerageDataDownloader.cs

Checklist

• I have completely filled out this template
• I have confirmed that this issue exists on the current master branch
• I have confirmed that this is not a duplicate issue by searching issues

Start by comparing DownloaderDataProvider/Models/BrokerageDataDownloader.cs with the PolygonDataDownloader implementation linked in the issue, focusing on the duplicated request, retry, pagination, output, and error-handling responsibilities. Define completion as a shared downloader abstraction that supports historical providers and Future universe files without each data source reimplementing that logic.