Cache: Add wp_cache_*_multiple functions.

Add new caching functions named `wp_cache_add_multiple`, `wp_cache_set_multiple` and `wp_cache_delete_multiple`. All of these functions allow for an array of data to be passed, so that multiple cache objects can be created / edited / deleted in a single function call. This follows on from [47938] where the `wp_cache_get_multiple` function was introduced and allowed for multiple cache objects to be received in one call. 

Props: spacedmonkey, tillkruess, adamsilverstein, flixos90, mitogh, pbearne. 
Fixes: #54574.


git-svn-id: https://develop.svn.wordpress.org/trunk@52700 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/pluggable.php

@@ -295,6 +295,20 @@ class Tests_Pluggable extends WP_UnitTestCase {
 						'group' => '',
 						'force' => false,
 					),
+					'wp_cache_set_multiple'              => array(
+						'data',
+						'group'  => '',
+						'expire' => 0,
+					),
+					'wp_cache_add_multiple'              => array(
+						'data',
+						'group'  => '',
+						'expire' => 0,
+					),
+					'wp_cache_delete_multiple'           => array(
+						'keys',
+						'group' => '',
+					),
 					'wp_cache_incr'                      => array(
 						'key',
 						'offset' => 1,