ZF2-138: CLONE - Limit the character set of cache ID in _validateIdOrTag

Description

There is no need to limit the character set to "[a-zA-Z0-9_]" in Zend_Cache_Core::_validateIdOrTag while using Memcached server as a Backend. It DOES accept characters like "-", "!" , ":" etc.

Comments

Cloned from ZF-10446 and fixed in ZF2 by design.

Now validating will be performed on adapter level and adapters like memcached don't validate the ids (now named keys).