fix: improvements and fixes to unnest support

[k-anshul]

1. unnest did not work for snowflake and bigquery.
2. Filter on unnest exploded the list for databricks.

Follow ups:

1. Subquery with unnest does not work on main.

Checklist:

• Covered by tests
• Ran it and it works as intended
• Reviewed the diff before requesting a review
• Checked for unhandled edge cases
• Linked the issues it closes
• Checked if the docs need to be updated. If so, create a separate Linear DOCS issue
• Intend to cherry-pick into the release branch
• I'm proud of this work!