Attach amplitude IDs to events in BigQuery

Created by: attfarhan

This unreverts https://github.com/sourcegraph/sourcegraph/commit/e4bc10429efe2a5b85d8a0f639479a7965f23c24. There is one change, where we won't send the event ID to BigQuery. It's not necessary to attach with events in the event that we need to do a backfill/replace data, so leaving it out.

Also, I have updated the relevant table in BigQuery to accept these two new fields.