Plaid sync domain improvements (#2267)

Breaks our Plaid sync process out into more manageable classes. Notably, this moves the sync process to a distinct, 2-step flow:

1. Import stage - we first make API calls and import Plaid data to "mirror" tables
2. Processing stage - read the raw data, apply business rules, build internal domain models and sync balances

This provides several benefits:

- Plaid syncs can now be "replayed" without fetching API data again
- Mirror tables provide better audit and debugging capabilities
- Eliminates the "all or nothing" sync behavior that is currently in place, which is brittle

app/views/shared/_money_field.html.erb

@@ -34,6 +34,7 @@
         min: options[:min] || -99999999999999,
         max: options[:max] || 99999999999999,
         step: currency.step,
+        disabled: options[:disabled],
         data: {
           "money-field-target": "amount",
           "auto-submit-form-target": ("auto" if options[:auto_submit])