Support `wp_cache_{add,set,delete}_multiple()` functions

[harai]

Support wp_cache_{add,set,delete}_multiple() functions.

Ref: https://tarosky.slack.com/archives/C37E3P8SG/p1662715064118719

[waviaei]

Those three functions were implemented from WordPress 6.0, so need to check core version where applicable. Or else, we make 6.0 as the platform requirement.