Update distributions after post terms and meta is saved.

[peterwilsoncc]

Description of the Change

This moves the updating of distributions during edits from the save_post hook to the wp_after_insert_post hook.

In updates via both the classic and REST API, WordPress fires this hook after all terms and post meta is updated. This prevents the distribution of legacy data described in the issue.

Closes #399

How to test the Change

1. Install this mini-plugin that updates post meta with each save
2. On the main develop branch
   a) Create and distribute a post via the block editor
   b) Update the post
   c) Check the database -- observe the value of the post meta differs between source and distribution (one less)
3. Switch to this branch
4. Resave the post in the block editor
5. observe the post meta matches in both the source and distributed material.

Changelog Entry

Fixed - Ensure post meta and terms have saved prior to distribution.

Credits

Props @peterwilsoncc, @dinhtungdu, @dkotter, @timstl, @faisal-alvi.

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[peterwilsoncc]

I tried writing an E2E test for this (using tags rather than meta as the UI is already exposed) but I will need some help from some one more familiar with cyrpress.

[faisal-alvi]

@peterwilsoncc Code LGTM but the issue is not regenerating for me in the develop branch.

Please check the video:

dist-938-not-regenerating.mp4

Let me know if I'm not testing it correctly.

[peterwilsoncc]

@faisal-alvi Your tests process is correct, so I am unclear why we are seeing different results. I do have the classic editor installed so I wonder if it's an interaction with that. You'll see in the video that the distributed block on xu-distributor.local shows as a classic block.

Not in the video, I start on this branch so the values are in sync. The values go out of sync once I switch to develop. https://youtu.be/8grzn3YdWXk

[faisal-alvi]

@peterwilsoncc thanks for the video. I have retried and this time it regenerated for me in the develop and worked fine in the PR branch.