In [36566] a framework to lazily load metadata was introduced. This supported term and comment meta by default. In this commit, extends support for site ( blog ) meta. Site meta is not heavily used by core and is used by developers to extend multisite. In this change, `_prime_site_caches` and `WP_Site_Query` now call the new function `wp_lazyload_site_meta`. The function `wp_lazyload_site_meta` accepts an array of ids and adds them to the queue of metadata to be lazily loaded. The function `get_blogs_of_user` was updated to now lazily load site meta.
Follow on from [55671].
Props spacedmonkey, johnjamesjacoby, peterwilsoncc, mukesh27.
Fixes#58185.
git-svn-id: https://develop.svn.wordpress.org/trunk@55747 602fd350-edb4-49c9-b593-d223f7449a82