feat(medusa): Nested Categories Admin Update Endpoint (#2986)

What:

Introduces an admin endpoint that allows a user to update a product category

Why:

This is part of a greater goal of allowing products to be added to multiple categories.

How:

- Creates a route on the admin scope to update category
- Creates a method in product category services to update a category

RESOLVES CORE-956

.changeset/ninety-hairs-obey.md

@@ -0,0 +1,5 @@
+---
+"@medusajs/medusa": patch
+---
+
+feat(medusa): added admin endpoint to update product categories