Add bundle price per component rust example

[hannakebedom]

Problem

While working on https://github.com/Shopify/shopify-dev/pull/57187, I noticed that the bundles price per component example didn't have a rust version. I had to write one for https://github.com/Shopify/shopify-dev/pull/57187 so I'm including it here as well!

Solution

This PR adds a new Cart Transform example called "Cart Transform" that demonstrates how to implement bundle expansion functionality. The example shows how to:

1. Detect when a bundle product is added to the cart
2. Read bundle configuration from product metafields
3. Expand the bundle into its individual components as separate line items
4. Apply the correct pricing to each component

The example includes an implementation in Rust. It handles currency conversion by adjusting prices according to the presentment currency rate.

[tanusrixh]

LGTM! Although I'm now wondering if we should include rust examples for all the cart transform function examples that don't have rust versions...