Refactor unserialize calls to use _unserializeState

[TDannhauer]

Fixes erroneous data format for unserializing 'Horde_ActiveSync_Folder_Collection'

[TDannhauer]

What was going wrong
Those messages come from PHP’s unserialize() when it rejects the binary blob in horde_activesync_state (and related fields) before Horde’s own Horde_ActiveSync_Folder_*::unserialize() runs. Typical causes after an ActiveSync/Horde/PHP upgrade:

Stricter parsing in PHP 8.3+ (you’re on 8.4) — length/format checks are tighter.
Old state in the DB — blobs written with an older Horde or PHP serialization shape no longer match the current Serializable (C:) layout, so you get errors like “Erroneous data format for unserializing …” and “Error at offset …”.
Horde_ActiveSync_State_Sql::_loadStateFromResults() already treats unserialize() returning false as “no saved folder state” and rebuilds Horde_ActiveSync_Folder_Collection / Horde_ActiveSync_Folder_Imap as needed. So behaviour was mostly OK, but PHP still emitted warnings, and Horde logged them.

What we changed
A small helper _unserializeState() was added so those warnings are not passed through to Horde’s logger. All relevant unserialize() calls in that file now use it. Corrupt device rows in updateServerIdInState are skipped instead of fatalling. Device supported / properties fall back to [] if the blob is bad (same idea as an empty device).