Figure out flow of updating transactions for users

[burchandres]

Description

We need to figure out the flow of updating transactions for users. We get three different types of transactions:

• added: the newest transactions
• modified: transactions that have finally been posted to an account
• removed: transactions that have been refunded, etc.

My thoughts:

• Will be fired off in a taskiq background task (i.e. by running await sync_transactions(...))
• added transactions should just be pushed to database
• modified transactions should probably just update corresponding transactions that are persisted in postgres
• removed -- plaid suggests two ways: 1) remove from the database 2) tag as removed
  • I think we should just go with strategy 1 for now