feat: move create inventory to @medusajs/workflows (#5301)

**Why**
- We have some workflow-like flows in @medusajs/medusa. These should be moved over to the workflows package.
- Inventory Items <> Variant currently assume a 1-1 mapping. There should be support for a many-to-many mapping.

**What**
- PR introduces a feature flag for supporting many-to-many mappings for inventory and variants.
- Deletes legacy transaction handler in @medusajs/medusa.
- Adjusts existing createInventoryItems handler to remove dependency on variant data.

**Unkowns**
~~1. Couldn't find an existing test for the CreateProduct workflow. It should be tested that this still works as expected.~~
2. Have removed transaction managers as we should move to handling consistency through orchestration tooling. Are we ready for that?

packages/inventory/src/utils/build-query.ts

@@ -41,7 +41,7 @@ export function buildQuery<TWhereKeys extends object, TEntity = unknown>(
     where: buildWhere<TWhereKeys, TEntity>(selector),
   }
 
-  if ("deleted_at" in selector) {
+  if ("deleted_at" in selector || config.withDeleted) {
     query.withDeleted = true
   }
 

packages/inventory/src/utils/query.ts

@@ -70,6 +70,10 @@ export function getListQuery(
     queryBuilder.select(legacySelect.map((s) => "inv_item." + s))
   }
 
+  if (query.withDeleted) {
+    queryBuilder.withDeleted()
+  }
+
   if (query.order) {
     const toSelect: string[] = []
     const parsed = Object.entries(query.order).reduce((acc, [k, v]) => {