feat: lazy load heatmaps

[pauldambra]

I want to lazy load more features so that folk that aren't using them don't download them

here's heatmaps as an easy one to start with

[vercel[bot]]

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Name	Status	Preview	Updated (UTC)
posthog-js	✅ Ready (Inspect)	Visit Preview	Sep 28, 2024 9:06am

[github-actions[bot]]

Size Change: -1.27 kB (-0.05%)

Total Size: 2.8 MB

Filename	Size	Change
dist/all-external-dependencies.js	195 kB	+4.17 kB (+2.18%)
dist/array.full.js	352 kB	+964 B (+0.27%)
dist/array.full.no-external.js	351 kB	+964 B (+0.28%)
dist/array.js	164 kB	-1.86 kB (-1.12%)
dist/array.no-external.js	163 kB	-1.86 kB (-1.13%)
dist/main.js	165 kB	-1.86 kB (-1.12%)
dist/module.full.js	352 kB	+964 B (+0.27%)
dist/module.full.no-external.js	351 kB	+964 B (+0.28%)
dist/module.js	164 kB	-1.86 kB (-1.12%)
dist/module.no-external.js	163 kB	-1.86 kB (-1.13%)

ℹ️ View Unchanged

| Filename | Size | | :--- | :---: | | `dist/exception-autocapture.js` | 10.5 kB | | `dist/external-scripts-loader.js` | 2.35 kB | | `dist/heatmaps.js` | 6.72 kB | | `dist/recorder-v2.js` | 111 kB | | `dist/recorder.js` | 111 kB | | `dist/surveys-preview.js` | 59.8 kB | | `dist/surveys.js` | 66 kB | | `dist/tracing-headers.js` | 8.36 kB | | `dist/web-vitals.js` | 10.3 kB |

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