Multisite: Deprecate the blog_details filter.

`get_site()` has replaced `get_blog_details()` throughout core and is the recommended way to retrieve a current or single site object.

The `blog_details` filter is applied when full details are requested from `get_blog_details()`.

To ensure backwards compatibility in the switch to `get_site()`, this `blog_details` filter is now applied in `WP_Site::get_details()` and marked as deprecated with a note to rely instead on the `site_details` filter introduced in 4.6.

Props flixos90.
See #37102.
Fixes #38491.

Built from https://develop.svn.wordpress.org/trunk@38936


git-svn-id: http://core.svn.wordpress.org/trunk@38879 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/ms-blogs.php

@@ -240,10 +240,11 @@ function get_blog_details( $fields = null, $get_all = true ) {
 	 * Filters a blog's details.
 	 *
 	 * @since MU
+	 * @deprecated 4.7.0 Use site_details
 	 *
 	 * @param object $details The blog details.
 	 */
-	$details = apply_filters( 'blog_details', $details );
+	$details = apply_filters_deprecated( 'blog_details', array( $details ), '4.7.0', 'site_details' );
 
 	wp_cache_set( $blog_id . $all, $details, 'blog-details' );