feat: Add projection on inserted_at

[tomasfarias]

Problem

Since we added inserted_at batch exports are querying events based on inserted_at.

However, we are forced to include timestamp in the query to better utilize the sort key. It would be better if we could use a sort key based on inserted_at to optimize performance.

Moreover, due to the discrepancy between inserted_at and timestamp we are missing events that were historically loaded.

Changes

Add a migration that creates a projection with inserted_at in the sort key.

👉 Stay up-to-date with PostHog coding conventions for a smoother review.

How did you test this code?

[eboswort]

🙏 this MR would make a big difference for me and my team!

[posthog-bot]

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[eboswort]

Hi @tomasfarias, would you be able to help get this MR across the finish line? Really looking forward to being able to successfully sync all my posthog data to snowflake without missing stuff.

[fuziontech]

looks good to me! thanks for only doing this on 202309 partition

[fuziontech]

if you wanted to limit this to 202310 I would be even happier tbh!

[tomasfarias]

if you wanted to limit this to 202310 I would be even happier tbh!

Updated the materialization to 202310. Will merge if tests are green, thank you.