adding attributes field to MetaData for GroupBy and Join

[PolinaRodimova]

Summary

Adding attributes field to metadata for GroupBy and Join to pass company specific information

Why / Goal

Allow to passthrough some custom and company related information without adding dedicated fields

Test Plan

• Added Unit Tests
• Covered by existing CI
• Integration tested

Checklist

• Documentation update

Reviewers

[hzding621]

Today, kwargs is passed in GroupBy and Join which is saved in custom_json in metadata. It's intended that companies/users leverage kwargs and custom_json for their custom metadata, so I think we may not need to introduce another attributes parameter here. In your internal code, you can create wrappers for GroupBy/Join Python APIs with more explicit parameters for your custom metadata.

[nikhil-zlai]

Today, kwargs is passed in GroupBy and Join which is saved in custom_json in metadata. It's intended that companies/users leverage kwargs and custom_json for their custom metadata

@PolinaRodimova - if you go down the customJson route, could you please make a doc change for posterity's sake?