Fix Fatal errors : Cannot redeclare Horde_Imap_Client_Cache_Backend::…

[rahal]

I don't know how it happened, but __serialize and __unserialize where defined multiple times

[what-the-diff]

PR Summary

• Removal of __serialize() and __unserialize() methods
  In lib/Horde/Imap/Client/Cache/Backend.php, the methods responsible for preparing the object for serialization and restoring it from the serialized state have been removed. Additionally, the $this->_params property, which holds various configuration parameters, has been moved to the __unserialize() method.

• Changes to __serialize() in Cache.php
  In lib/Horde/Imap/Client/Cache/Backend/Cache.php, there are alterations to the __serialize() method, which is used to prepare the object for serialization. The new $this->save() method being added further strengthens the object's preparation before making a call to the parent class's __serialize() method, thereby enhancing the data preservation process.

[ralflang]

Looks like the previous PR went wrong