chore: add more Stripe test cases

[burmecia]

What kind of change does this PR introduce?

This PR is to add more smoke test cases for Stripe FDW.

What is the current behavior?

Currently, there are only 3 test cases:

1. Balance
2. Customers
3. Subscriptions

What is the new behavior?

More test cases will be added:

1. Balance
2. Balance Transactions
3. Charges
4. Customers
5. Invoices
6. PaymentIntents
7. Products
8. Subscriptions

Additional context

N/A

[olirice]

looks great!

for the tables that support insert, update, and where clause push down could that included too?

[burmecia]

looks great!

for the tables that support insert, update, and where clause push down could that included too?

Code added, but the Stripe mock container doesn't support data modify, so I commented it out.

https://github.com/stripe/stripe-mock#current-state-of-development