feat(promotion, dashboard, core-flows, cart, types, utils, medusa): tax inclusive promotions (#12412)

* feat: tax inclusive promotions

* feat: add a totals test case

* feat: add integration test

* chore: changeset

* fix: typo

* chore: refactor

* fix: tests

* fix: rest of buyget action tests

* fix: cart spec

* chore: expand integration test with item level totals

* feat: add a few more test cases

---------

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

packages/core/core-flows/src/cart/steps/prepare-adjustments-from-promotion-actions.ts

@@ -132,6 +132,7 @@ export const prepareAdjustmentsFromPromotionActionsStep = createStep(
       .map((action) => ({
         code: action.code,
         amount: (action as AddItemAdjustmentAction).amount,
+        is_tax_inclusive: (action as AddItemAdjustmentAction).is_tax_inclusive,
         item_id: (action as AddItemAdjustmentAction).item_id,
         promotion_id: promotionsMap.get(action.code)?.id,
       }))