Add invalid id token handling for `current_shopify_domain` method

[kirillplatonov]

What this PR does

Fixes #1866

When app root URL is opened directly outside of iframe it used to redirect to /login page. With Token Exchange auth it now throws an exception ShopifyAPI::Errors::MissingJwtTokenError because current_shopify_domain method is called by ShopifyApp::FrameAncestors and it doesn't have any error handling at the moment.

In this PR I added missing error handling for current_shopify_domain and redirect to /login work again. https://github.com/Shopify/shopify_app/assets/839922/da1eb29c-1f7f-4f26-b8ea-637778cfd8b0

Reviewer's guide to testing

To reproduce the issue:

1. Launch the app that uses Token Exchange auth
2. Open root URL outside of iframe
3. You should see ShopifyAPI::Errors::MissingJwtTokenError

Checklist

Before submitting the PR, please consider if any of the following are needed:

• [x] Update CHANGELOG.md if the changes would impact users
• [x] Update README.md, if appropriate.
• [x] Update any relevant pages in /docs, if necessary
• [x] For security fixes, the Disclosure Policy must be followed.

[kirillplatonov]

cc @zzooeeyy @paulomarg

[matteodepalo]

Hi @kirillplatonov thank you for opening this PR and the others, the team will look at them soon.

[kirillplatonov]

@matteodepalo Thanks guys! Let me know if any adjustments are necessary.

[kirillplatonov]

@zzooeeyy Awesome! Resolved conflicts and ready for merge.