chore(content-distribution): log distribution elapsed time

[miguelpeixe]

Implement logging the time between the distribution dispatch and the post being updated in the destination.

Testing

1. Make sure you have NEWSPACK_NETWORK_DEBUG set to true
2. Distribute a post and wait for it to arrive at the destination
3. Check the destination logs and confirm you have the following entry: Post <post id> updated <elapsed time> seconds after distribution
4. If your destination is connected to logstash, locate the entry filtering by the error_code: newspack_network_post_updated

[github-actions]

Hey @miguelpeixe, good job getting this PR merged! 🎉

Now, the needs-changelog label has been added to it.

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If it does, please add an entry to our shared document, with screenshots and testing instructions if applicable, then remove the label.

Thank you! ❤️

[matticbot]

🎉 This PR is included in version 2.6.0-alpha.1 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀

[matticbot]

🎉 This PR is included in version 2.6.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀