Migrate fullpage redirect to App Bridge CDN

[kirillplatonov]

What this PR does

Switching from hardcoded AppBridge 3 version to AppBridge CDN. This removes the need to pass params[:host] for fullpage_redirect_to helper and fixes redirect with token exchange auth. I manually tested it with both token exchange and legacy auth.

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

[kirillplatonov]

@matteodepalo please take a look at this one too. It's important upgrade to move forward with migration to id_token.

[matteodepalo]

Hi @kirillplatonov, we're taking a look now.

[kirillplatonov]

@byrichardpowell made adjustments based on your feedback. Code become even simpler 👍