New optional SDK config: skipExportData

We've added a new optional configuration [skipExportData](https://docs.oneschema.co/docs/javascript#skipexportdata) that changes the behavior of the success event when not including a webhookKey. Instead of receiving all of the data from a user's import, you can now just receive the sheet_id. With it, you may query our API to download the file.

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Recommendation

This configuration is best used if you expect to receive large files from your users and don't want them to wait for their data to be processed (eg. 500MB+).