feat: Add necessary middlewares for tax inclusive pricing (#7827)

We are adding tax inclusive pricing calculation when listing products.

Two things to keep in mind:
- `region_id` will be required if you request calculated prices.
- We won't accept `currency_code` anymore, as that will come from the region info (since ultimately a cart and its currency are tied to a region)

REF CORE-2376
DEPENDS ON #8003

packages/core/utils/src/totals/index.ts

@@ -2,6 +2,7 @@ export * from "./cart"
 export * from "./create-raw-properties-from-bignumber"
 export * from "./line-item"
 export * from "./math"
+export * from "./tax"
 export * from "./promotion"
 export * from "./shipping-method"
 export * from "./transform-properties-to-bignumber"

packages/core/utils/src/totals/tax/index.ts

@@ -31,3 +31,24 @@ export function calculateTaxTotal({
 
   return taxTotal
 }
+
+export function calculateAmountsWithTax({
+  taxLines,
+  amount,
+  includesTax,
+}: {
+  taxLines: Pick<TaxLineDTO, "rate">[]
+  amount: number
+  includesTax?: boolean
+}) {
+  const tax = calculateTaxTotal({
+    taxLines,
+    includesTax,
+    taxableAmount: amount,
+  })
+
+  return {
+    priceWithTax: includesTax ? amount : MathBN.add(tax, amount).toNumber(),
+    priceWithoutTax: includesTax ? MathBN.sub(amount, tax).toNumber() : amount,
+  }
+}