Add boilerplate plugin for Jetpack Promote

[gravityrail]

Fixes #

Changes proposed in this Pull Request:

Jetpack product discussion

Does this pull request change what data or activity we track or use?

Testing instructions:

• Go to '..'

[github-actions[bot]]

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Promote plugin:

• Next scheduled release: May 3, 2022.
• Scheduled code freeze: April 25, 2022.

[jeherve]

closing as this was eventually implemented in https://packagist.org/packages/automattic/jetpack-blaze