#3630294: Show a site's override revisions only to those who may override there (!6) · Merge requests · project / sites_diff

The revision overview shows a site's override revisions only to an account with override access on that site, or a real global "Administer sites", and carries the cacheability of those access results. Each table is headed by the site's label. The archived sites_group branch is removed. New functional test: RevisionOverviewSiteAccessTest.
RevisionOverviewFormDecorator imports SitePluginManagerInterface from Drupal\sites\Plugin; the old namespace ended every admin page that runs a form decorator in a TypeError.
UI texts and docblocks that the generated reference of the Sites documentation shows are rewritten, and the README points to it.

The commits are kept separate on purpose; each one stands on its own.

#3630294: Show a site's override revisions only to those who may override there