Add navigatorInterface + messageBridge support

[joshliebe]

Task/Issue URL: https://app.asana.com/0/488551667048375/1208697679300718/f

Description

• Adds a new package to the content-scope-scripts-impl module to inject the navigatorInterface JSON from the privacy config.
• Also adds the related messageBridge C-S-S feature which is required for SERP<->native communication.

Steps to test this PR

navigatorInterface

• Check out this branch
• Apply the patch linked in the task
• Go to https://privacy-test-pages.site/features/navigator-interface.html
• Verify the page looks like this:

messageBridge

• Go to duckduckgo.com
• Open Chrome and go to chrome://inspect
• In the console, type: navigator.duckduckgo.createMessageBridge(“aiChat").notify("helloWorld”)
• Verify that you see the following:

[joshliebe]

• Add navigatorInterface + messageBridge support #5461 👈 (View in Graphite)
• develop

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