✨[amp-ad] Support new ad attribution reporting API

[calebcordry]

Description

https://developer.chrome.com/docs/privacy-sandbox/attribution-reporting/

• [x] Introduce new browserAdConversion functionality to amp-ad-exit
• [x] Support feature rollout monitoring with ATTRIBUTION_REPORTING_STATUS macro
• [x] Add origin trial tokens
• [x] Add feature policy to 3p fallback ad frames

[stale[bot]]

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