AC-16602: API Documentation

[shashi011]

Purpose of this pull request

This pull request (PR) ...

Affected pages

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Links to Magento Open Source code

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[shashi011]

@keharper
Please review the following new REST API endpoints added to the Admin API schema (Commerce 2.4.8):
Endpoints:
POST /V1/carts/{cartId}/balance/apply - Apply store credit balance to a cart
DELETE /V1/carts/{cartId}/balance/unapply - Unapply store credit balance from a cart
GET /V1/customers/{customerId}/balance/{websiteId} - Get store credit balance for a customer and website
Changes:
Added endpoint definitions, tags, and tag groups
Created schema definition: customer-balance-data-balance-interface
File: src/openapi/admin-schema-2.4.8.yaml
Please review for correctness and consistency with existing API patterns. Also, please confirm if we need to update any other files or documentation for these REST changes. Thanks!