We're keeping the `store-integrations-list` extension point name for backwards compatibility, otherwise I renamed all "integration" occurences in the views and also the routes.
Note: We still refer to external software like WooCommerce, Drupal, Magento and such as "integrations", I think that distinction makes sense.
Closes#3594.
Added dedicated endpoint that generates an invoice or returns an existing one as needed for a shopify order
Added rate limiter to shopify endpoint to prevent abuse
Reduce shopify js to a small file
Use events from btcpay modal to reduce constant pinging to btcpay server
Register invoice payment failures on the shopify backend.
