fix(cache): delegate legacy Hashtable storage to modern adapter

[TDannhauer]

fix(cache): delegate legacy Hashtable storage to modern adapter

Summary

• Fix TypeError in ActiveSync and other code paths that use the legacy Horde_Cache API with a modern Horde\HashTable\HashTable backend (e.g. Memcache).
• When Horde_Core_Factory_Cache injects a PSR-4 Horde\HashTable\HashTable instance, Horde_Cache_Storage_Hashtable now delegates to Horde\Cache\HashtableStorage instead of calling the old array-based get() API.
• Legacy Horde_HashTable backends are unchanged and still use the existing code path.

Problem

After the FRAMEWORK_6_0 HashTable modernization, Horde\HashTable\Driver\Memcache::get() accepts only a string key. The legacy cache storage adapter still called:

$this->_hash->get($query); // $query is an array

That surfaced during ActiveSync requests via:

Horde_Perms_Sql->exists() → Horde_Cache->get() → Horde_Cache_Storage_Hashtable->get() → Memcache::get(array)

Horde_Core_Factory_Cache already documents routing modern HashTable instances through HashtableStorage, but that was never implemented in the storage class.

Solution

Detect Horde\HashTable\HashTable in _initOb() and wrap it with Horde\Cache\HashtableStorage. Delegate get(), set(), and expire() to that adapter, which correctly uses getMultiple() and the modern TTL API.

Test plan

• Configure cache driver Hashtable with Memcache backend ($conf['cache']['driver'] = 'Hashtable', $conf['hashtable']['driver'] = 'Memcache').
• Trigger an ActiveSync request (e.g. mobile device sync or rpc.php ActiveSync endpoint).
• Confirm no TypeError: Memcache::get(): Argument #1 ($key) must be of type string, array given in Horde logs.
• Verify cache read/write via legacy adapter:

  $storage = new Horde_Cache_Storage_Hashtable(['hashtable' => $hash, 'prefix' => 'horde']);
  $storage->set('test_key', 'test_value', 3600);
  $storage->get('test_key', 3600); // returns 'test_value'

• Confirm legacy Horde_HashTable backends still work if used directly.

[ralflang]

Mind #4 and related horde/Core#131

[ralflang]

Superseded by 3.0.0RC2 a4ebb16