fix: Fix $is_identified

[robbie-c]

Changes

Fix a big that was introduced in #1114 where $is_identified can be false even when the user is identified.

Instead of letting the session_persistance take priority over the regular persistance, return true if either persistance know the user is identified.

Also added a test to cover this case, and some scripts + docs to make it simpler to use the nextjs playground as a place to test posthog-js changes.

Checklist

• Tests for new code (see advice on the tests we use)
• Accounted for the impact of any changes across different browsers
• Accounted for backwards compatibility of any changes (no breaking changes in posthog-js!)

[github-actions]

Size Change: +276 B (0%)

Total Size: 944 kB

Filename	Size	Change
dist/array.full.js	225 kB	+69 B (0%)
dist/array.js	124 kB	+69 B (0%)
dist/es.js	125 kB	+69 B (0%)
dist/module.js	125 kB	+69 B (0%)

ℹ️ View Unchanged

Filename	Size
dist/exception-autocapture.js	12.1 kB
dist/recorder-v2.js	106 kB
dist/recorder.js	106 kB
dist/surveys-module-previews.js	62 kB
dist/surveys.js	58.3 kB

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