Reestablish message port on bfcache restore

[tunetheweb]

As per: https://developer.chrome.com/blog/bfcache-extension-messaging-changes we need to add some extra code for bfcache restores for future breaking changes in Chrome.

See also https://github.com/GoogleChrome/web-vitals-extension/pull/161#issuecomment-1961671068

To repeat without this fix:

• Launch Chrome >= 123 with --enable-features=DisconnectExtensionMessagePortWhenPageEntersBFCache
• Install the extension
• Pin it to extension bar
• Go to https://www.tunetheweb.com/experiments/softnavsdemo/#1
• Note Green circle badge
• Click "Simulate slow interaction"
• Note badge changes to red triangle
• Reload to reset back to Green Circle
• Go to https://www.example.com/
• Go back to restore from bfcache
• Note badge stays at grey 😔
• Click "Simulate slow interaction"
• Note badge stays at grey 😔

Use this branch, and repeat above test, and note last two 😔 are now 😁

FYI: @lozy219 @oliverdunk