chore: Remove FlagRouter from core (#4710)

* Allow nested feature flags

* clean up

* Create loud-wombats-shave.md

* add warning

* Add more tests

* Address PR comments

* add back boolean check

* Replace core flag router with utils one

* lol - actually remove it

* Create eleven-doors-roll.md

---------

Co-authored-by: carlos-r-l-rodrigues <rodrigolr@gmail.com>

packages/medusa/src/services/__tests__/discount.js

@@ -1,5 +1,5 @@
 import { IdMap, MockManager, MockRepository } from "medusa-test-utils"
-import { FlagRouter } from "../../utils/flag-router"
+import { FlagRouter } from "@medusajs/utils"
 import DiscountService from "../discount"
 import { TotalsServiceMock } from "../__mocks__/totals"
 import { newTotalsServiceMock } from "../__mocks__/new-totals"