#6007299 Storefront: Add unique theme demo URL for Storefront as a temporary workaround

Changes proposed in this Pull Request

• Temporarily update the getThemeDemoUrl selector to point to a special demo site for Storefront rather than the automatically generated one at wp-themes.com
• Update direct references to the demo site on the theme sheet to the unique demo site for Storefront
• Also updates button copy for “Open Live Demo” to use Title case

Fixes #37658

We talked about whether we should do a “hacky” fix like this and decided it’s probably worth it, since it does not look like we’ll be adding Storefront to WP.com soon.

Before

After

Testing instructions

• Switch to this PR
• Navigate to /themes for an Atomic site
• Search for Storefront under “Show all themes”
• Click the “Live demo” link under the theme’s ellipsis menu; it should first open an iFrame preview, which then redirects you to https://themes.woocommerce.com/storefront/ in a new tab (this is the known behavior for all themes uploaded by a user ie. not native to WP.com)
• View the theme sheet for Storefront (click on the screenshot); you should see https://themes.woocommerce.com/storefront/as the URL when you hover over the “Open live demo” button or the theme screenshot on the right
• Clicking on either the screenshot or the “Open live demo” button should open the iFrame preview, which then redirects you to https://themes.woocommerce.com/storefront/ in a new tab
• Make sure other themes’ demo links work as expected; themes native to WP.com will open demo sites in the iFrame preview, themes that have been installed by the user will open in a new tab