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>

.changeset/rich-shrimps-learn.md

@@ -0,0 +1,6 @@
+---
+"@medusajs/medusa": minor
+---
+fix: Gift cart tax claculation wrongly calculated
+
+Adds tax_rate column to gift_card table to calculate tax accurately for a gift card. This change includes a backfill migration to update gift cards that were already created.