Add parameter to go back for theme links in cys intro screen

[ilyasfoo]

Changes proposed in this Pull Request:

Partially addresses https://github.com/woocommerce/woocommerce/issues/41230

How to test the changes in this Pull Request:

1. Set up a latest WordPress according to this guide: p6q8Tx-3Je-p2
2. Make sure to enable customize-store feature flag
3. Go to Home and click on Customize your store task
4. In the intro screen, click on any of the themes
5. Observe the URL navigated has from=customize-store. For example, /theme/tsubaki/wooexpresstestingsite.wpcomstaging.com?from=customize-store

Other information:

• [ ] Have you added an explanation of what your changes do and why you'd like us to include them?
• [ ] Have you written new tests for your changes, as applicable?

FOR PR REVIEWER ONLY:

• [ ] I have reviewed that everything is sanitized/escaped appropriately for any SQL or XSS injection possibilities. I made sure Linting is not ignored or disabled.

[github-actions[bot]]

Size Change: 0 B

Total Size: 196 kB

ℹ️ View Unchanged

| Filename | Size | | :--- | :---: | | `./build/53.js` | 1.05 kB | | `./build/index.css` | 883 B | | `./build/index.js` | 121 kB | | `./build/marketing.js` | 58 kB | | `./build/payment-gateway-suggestions.css` | 1.25 kB | | `./build/payment-gateway-suggestions.js` | 6.45 kB | | `./build/plugins.js` | 3.92 kB | | `./build/style-index.css` | 2 kB | | `./build/style-marketing.css` | 805 B |

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