* Decouple Shopify from Store
* Decouple shopify from store blob
* Update BTCPayServer.Tests.csproj
* Make sure shopify obj is set
* make shopify a system plugin
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.