Show a notice on the landing page if this extension does not support their store country

[eason9487]

Closes #251

Changes proposed in this pull request

• Expose store country and whether it's supported by Pinterest Ads to client-side via inline JavaScript.
• Implement an unsupported country warning with <Notice> component and show it on the landing page when store country is not supported.

Additional notes

⚠️ Currently the extension is based on “store location” based on WP Admin > WooCommerce > Settings > General location information.

• 💡 Before merging we'll confirm if the notice content is approved cc @shivanarrthine

Screenshots

Detailed test instructions

1. Go to the General tab of WC Settings. Change the "Country / State" option to one of the unsupported countries.
2. Go to the landing page: /wp-admin/admin.php?page=wc-admin&path=%2Fpinterest%2Flanding
3. It should show an unsupported notice at the page top.
   • Click on the "Change your store’s country here", it should bring you to WC Settings.
   • Click on the "Read more about supported countries", it should open a new tab to Pinterest's help page.

Changelog entry

Add - Show a notice on the landing page if this extension does not support their store country.

[eason9487]

📝
I tried to get the ads availability list from Pinterest API, but the API requires the read_pin_promotions permission first. In addition, the read_pin_promotions permission is not currently asked by this extension, and the landing page does not yet require authorization, so it seems unable to use the API in our use case.

[jconroy]

so it seems unable to use the API in our use case.

Perfect, thanks for the investigation @eason9487

[ianlin]

Tested in local and it worked perfectly!

[shivanarrthine]

Before merging we'll confirm if the notice content is approved

Confirming that the notice content is approved. @eason9487