This fixes the discount_ calculation logic and promotion tax inclusiveness calculation (#12960)

* This fixes the discount_ calculation logic

* This fixes the adjustment to be handled as a subtotal value in every calculation and applies the tax inclusive logic on the promotion value itself

* Added some testcases and revoked some changes to improve testing output

* Fixed a test case based on feedback

* Corrected promotion/admin test cases

* Corrected cart/store test case

* Improved cart/store test cases for more robust promotion testing considering tax inclusion flags

* Remove unnessary changes as adjustments now automatically are subtotals and therefore the tax inclusive flag does not need to be applied again

* Remove adjustments->is_tax_inclusive usage everywhere

* Migration script to remove is_tax_inclusive in cart line item adjustment

* Forgot to adjust one more testcase

* Corrections based on fPolic feedback

* Refactored PR to consider feedback from oliver

* Added more testcases for promotion in cart

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Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

packages/medusa/src/api/store/carts/query-config.ts

@@ -35,6 +35,7 @@ export const defaultStoreCartFields = [
   "promotions.id",
   "promotions.code",
   "promotions.is_automatic",
+  "promotions.is_tax_inclusive",
   "promotions.application_method.value",
   "promotions.application_method.type",
   "promotions.application_method.currency_code",
@@ -77,6 +78,7 @@ export const defaultStoreCartFields = [
   "items.adjustments.code",
   "items.adjustments.promotion_id",
   "items.adjustments.amount",
+  "items.adjustments.is_tax_inclusive",
   "customer.id",
   "customer.email",
   "customer.groups.id",