fix(types): add missing inventory_items to input of createProductsWorkflow (#10892)

The `createProductsWorkflow` allows passing an `inventory_items` property to assign the inventory items of a product variant, and we even pass it in the `/admin/products` API route when creating a variant, but the workflow's input type doesn't include that property. This PR adds it to the workflow's input type.

.changeset/angry-jobs-prove.md

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+"@medusajs/types": patch
+---
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+fix(types): add missing inventory_items to input of createProductsWorkflow