feat: add experiment facets to oversight

[shsteimer]

Description

Adds the experiment checkpoint as well as source/target facets.

Related Issue

Fix #803

Motivation and Context

allows comparing CWV impact of experiments, as well as drilling down on other checkpoints (clicks, etc.) when experiment is running.

How Has This Been Tested?

https://oversight-experiments--helix-website--adobe.aem.page/tools/oversight/explorer.html?domain=www.aem.live&filter=&view=year&=performance&checkpoint=click&checkpoint=experiment&experiment.source=short-home&experiment.target=challenger-1&domainkey=&conversion.checkpoint=click

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[aem-code-sync]

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Commits

• 9504af8 ✅ (latest)

[aem-code-sync]

	Page	Scores	Audits	Google
📱	/tools/oversight/explorer.html?domain=www.aem.live&filter=&view=year&=performanc e&checkpoint=click&checkpoint=experiment&experiment.source=short-home&experiment .target=challenger-1&domainkey=&conversion.checkpoint=click
🖥️	/tools/oversight/explorer.html?domain=www.aem.live&filter=&view=year&=performanc e&checkpoint=click&checkpoint=experiment&experiment.source=short-home&experiment .target=challenger-1&domainkey=&conversion.checkpoint=click