chore: log browser offline status

[jurajmajerik]

Changes

Add Browser is offline to logs when the browser is offline.
We're seeing frequent "Failed to fetch feature flags" errors with one of our users and want to rule out connection issues as the cause.

Slack thread: https://posthog.slack.com/archives/C0522G09STW/p1698051029628329

Checklist

• Tests for new code (see advice on the tests we use)
• Accounted for the impact of any changes across different browsers

[github-actions]

Size Change: +220 B (0%)

Total Size: 723 kB

Filename	Size	Change
dist/array.full.js	176 kB	+55 B (0%)
dist/array.js	118 kB	+55 B (0%)
dist/es.js	118 kB	+55 B (0%)
dist/module.js	118 kB	+55 B (0%)

ℹ️ View Unchanged

Filename	Size
dist/recorder-v2.js	95.1 kB
dist/recorder.js	58.4 kB
dist/surveys.js	39.6 kB

_{compressed-size-action}

[pauldambra]

really interested to see how this goes....

would be cool, for example, to stop retrying while offline