Welcome scope Promotion#coupons

It makes sense sometimes to only fetch promotions where a coupon code is
present
Better errors on coupon code failing

Assuming everything that wouldn't activate properly was "already
applied" doesn't work since anything that fails to activate but wasn't
"already applied" shows up to an end-user as "already applied". By
explicitly checking for coupons already applied we can put a more
generic error if activate fails.

Fixes #4781
Refactor stock transfers variant select JS - Allow user to search for a variant by name or SKU, rather than just returning the first 25 items from a stock location

Closes #4795
update the default email template to include all the proper taxes, shipments and adjustments

Fixes #4798
Update payment risk assessment, and fix broken specs. Fixes #4630