Upserts should deal with missing relationships

[Copple]

Chore

Describe the chore

• the schema has a relationships between tables
• if we try to upsert data which is missing foreign data then the upsert will fail (i.e. we might be backfilling the data while a webhook is called)
• when we are upserting records, we should check that the related data exists first
• if it doesnt exist, fetch it from Stripe and upsert it