Update Jetpack_Notifications::print_js() to be CSP-compatible

[westonruter]

Proposed changes:

To be compatible with CSP, the nonce attribute needs to be able to be inserted into SCRIPT tags generated by WordPress. This is made possible when using wp_print_script_tag() and wp_print_inline_script_tag().

This has been slowly rolling out to WordPress core. For context, see these Trac tickets:

• #58664: Eliminate manual construction of script tags in WP_Scripts and of inline scripts on frontend/login screen
• #39941: Allow using Content-Security-Policy without unsafe-inline
  
• #63806: Bundled themes: Scripts are printed directly without using wp_print_script_tag()/wp_print_inline_script_tag()
• #59446: Use script helper functions in admin to enable Content-Security-Policy opt-in
  

This also improves the exporting of data from PHP to JS per https://sirre.al/2025/08/06/safe-json-in-script-tags-how-not-to-break-a-site/

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

Does this pull request change what data or activity we track or use?

Testing instructions:

1. Install the Strict CSP plugin.
2. Ensure the admin bar Notes 🔔 dropdown works on the frontend.

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

• ✅ Include a description of your PR changes.
  
• ✅ Add testing instructions.
  
• ✅ Specify whether this PR includes any changes to data or privacy.
  
• 🔴 Add changelog entries to affected projects
  

This comment will be updated as you work on your PR and make changes. If you think that some of those checks are not needed for your PR, please explain why you think so. Thanks for cooperation 🤖

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