feat: acquisition checkpoint

[ekremney]

This approach combines utm , paid, and email into one checkpoint = acquisition. Uses document.referrer as source, and the combined value as target:

example from real use-case

checkpoint=acquisition
source=https://www.youtube.com/
target={ utm_medium: 'youtube', utm_source: 'video', others: ['gclid'] }

referrer and query params collected are being processed by rum-collector via https://github.com/adobe/helix-rum-collector/pull/358

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• [ ] make sure to link the related issues in this description
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Related Issues

Thanks for contributing!

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 41.43%. Comparing base (645c20f) to head (81bc11a). Report is 22 commits behind head on 1.x.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## 1.x #223 +/- ## ========================================== - Coverage 45.38% 41.43% -3.96% ========================================== Files 1 1 Lines 271 251 -20 ========================================== - Hits 123 104 -19 + Misses 148 147 -1 ```

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[github-actions[bot]]

This PR will trigger a minor release when merged.

[trieloff]

226 will be helpful once you need to test this.