New functions `wp_insert_site( $data )`, `wp_update_site( $id, $data )` and `wp_delete_site( $id )` are introduced to manage site rows in the `wp_blogs` table, forming the new CRUD API together with the existing `get_site()` / `get_sites()`. The new API provides various benefits over the previously existing API, fixing several cache invalidation issues and being hook-driven so that normalization and validation of the passed data can be fully customized.
New hooks introduced as part of this are the actions `wp_insert_site`, `wp_update_site`, `wp_delete_site`, `wp_validate_site_data` and the filter `wp_normalize_site_data`.
At this point, `wp_insert_site()` does not handle setting up the site's database tables, and `wp_delete_site()` does not handle dropping the site's database tables, so the two can not yet be used directly as full replacements of `wpmu_create_blog()` and `wpmu_delete_blog()`. Managing the site's database tables will be added via hooks as part of the follow-up ticket #41333.
The existing functions `wpmu_create_blog()`, `update_blog_details()`, and `wpmu_delete_blog()` make use of the respective new counterpart and will be obsolete once #41333 has been completed.
Props flixos90, jeremyfelt, spacedmonkey.
Fixes#40364.
git-svn-id: https://develop.svn.wordpress.org/trunk@43548 602fd350-edb4-49c9-b593-d223f7449a82
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