Auto lookup subscriptions

[ideadude]

You can import members with existing gateway subscriptions by making sure that the necessary order and subscription_transaction_id columns are filled in. However, this data is not always available and there is a big opportunity for user error to forget or mess this data up.

Let's create an option to just search for subscriptions at the gateway by email address. We could code this to work for Stripe for sure. Braintree probably. PayPal is an issue because the email is often different, but we could perhaps generate a report.

We would want to run this in the background because of the number of required API hits.