Meta API - get_rating_categories

## Description

In version 1.1.0 of beckn, a new set of APIs has been introduced that can be used by the BAPs to fetch the meta information. One of the API is get_return_reasons. In this BAP fetches the list of return rating categories from BPP. In Strapi plugin we need to implement the get_rating_categories.

1. Create a suitable datamodel in Strapi , check if any existing data model can be used to provide the detail.
2. Create an endpoint in webhook to handle the request.
3. Implement the query logic to fetch the requested detail.
4. Test the endpoint from Strapi and the generic client layer.
5. Write unit test case for get rating categories API.

## Goals

- [ ] Implement fetch return rating reasons API in Strapi

## Expected Outcome

Strapi should be able to serve the get_rating_categories API call from BAP.

## Acceptance Criteria

- [ ] Correct result is provided to BAP when a request for rating categories is made to Strapi BPP.

## Implementation Details

It should be part of the strapi pugin and must follow the specification details here - https://github.com/beckn/protocol-specifications/blob/master/api/meta/build/meta.yaml

### Tech Skills Needed:

Strapi plugin development
Node Js

### Complexity

Medium

### Category

Enhancement

### Sub Category

Strapi plugin enhancement

Start with the meta API specification in meta.yaml, then inspect the existing Strapi plugin webhook and generic client handling for comparable APIs. Design or reuse a suitable data model, implement the request and query flow, and verify the endpoint plus unit tests. Done means the BAP receives the correct rating categories response.

Written by the indexing model from the issue text.