Fix configurable product Add To Cart API with superAttribute #569

[rohansingh754]

### 🐞 Bug Fix: Configurable Product Add To Cart with Super Attributes

This PR fixes an issue where configurable products could not be added to the cart via the Add To Cart API when `super_attribute` was provided.

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### ❌ Problem
When calling the Add To Cart API (`/api/checkout/cart/add`) for a configurable product and passing `super_attribute`, the API fails to resolve the correct child product.

As a result, the API returns the following error:

```json
{
  "errors": [
    {
      "message": "Options are missing for this product."
    }
  ]
}

This happens because the API does not dynamically match the selected super_attribute options with the corresponding configurable child product.

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✅ Solution

• Dynamically maps the provided super_attribute (attribute_id => option_id).
• Iterates through configurable product indexes.
• Matches all selected super attributes against available child product combinations.
• Correctly identifies and assigns the selected configurable option.

This solution works for:

• Any number of configurable attributes (e.g. size, color, material, etc.)
• Both increased or reduced attribute sets
• GraphQL and REST Add To Cart APIs

📌 Related Issue

Fixes #569

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🧪 Impact

• Fixes configurable Add To Cart API behavior
• No breaking changes
• Backward compatible