Feat(medusa, medusa-js, medusa-react): order edit item update (#2246)

**what**
Support `updateLineItem` which does the following:
- If no item change exist then create a new one and attaches the clone item with the adjustments and tax lines
- if an item change exists then delete/create adjustments and tax lines and update the cloned item quantity

**Tests**
- Unit tests core + client
- integration tests
  - When no item change already exists
  - When an item change already exists

FIXES CORE-497

packages/medusa-react/mocks/handlers/admin.ts

@@ -1712,7 +1712,7 @@ export const adminHandlers = [
         order_edit: {
           ...fixtures.get("order_edit"),
           requested_at: new Date(),
-          status: "requested"
+          status: "requested",
         },
       })
     )
@@ -1742,6 +1742,22 @@ export const adminHandlers = [
     )
   }),
 
+  rest.post("/admin/order-edits/:id/items/:item_id", (req, res, ctx) => {
+    return res(
+      ctx.status(200),
+      ctx.json({
+        order_edit: {
+          ...fixtures.get("order_edit"),
+          changes: [
+            {
+              quantity: (req.body as any).quantity,
+            },
+          ],
+        },
+      })
+    )
+  }),
+
   rest.get("/admin/auth", (req, res, ctx) => {
     return res(
       ctx.status(200),