Adds the https://api.w.org/action-set-homepage and https://api.w.org/action-set-posts-page links to pages in the edit context, like action-trash (#63670). Published pages get them when the current user can manage_options, except the current homepage and posts page.
The editor uses these links for its "Set as homepage" and "Set as posts page" actions, so it no longer has to read the site settings. And the actions can just rely on the current self contained item information without additional API changes or requests.
Gutenberg PR: https://github.com/WordPress/gutenberg/pull/84932
Javascript required