fix(medusa): gift card values & taxes are calculated correctly (#2777)

* chore: tax_rate is added to giftcards

* chore: minor

* chore: update gift card tax calculations to look at giftCard.tax_rate

* chore: gift card transactions use tax rate from gift card for legacy

* fix: gift cart total check for transaction should check the length

* chore: use tax exclusive cost + use giftcard tax rate for gctransactions + refactor

* chore: fix integration test

* chore: address issues brought up in comments

* chore: move gift card creation as a part of order service on order placed

* chore: add type handling for gift card creation

* chore: fix specs

* chore: use taxLines to calculate tax of a gift card

* chore: specs for line items containing gift cards and without

* chore: add integration specs + fix tax rate bug

* chore: round totaling + add GC application specs

* chore: cleanup trialables

* chore: write migration script to backfill gift cards with null tax_rate

* chore: update legacy totals service for gift cards

* chore: add changeset

* chore: address PR review changes

* chore: fix tests based on new totals calc

* chore: address review comments

Co-authored-by: adrien2p <adrien.deperetti@gmail.com>
Co-authored-by: Oliver Windall Juhl <59018053+olivermrbl@users.noreply.github.com>

integration-tests/api/__tests__/totals/orders.js

@@ -139,6 +139,7 @@ describe("Order Totals", () => {
         region_id: region.id,
         value: 160000,
         balance: 160000,
+        tax_rate: 25,
       })
 
       // Add variant 1 to cart