Check ext.weapon.equipId potential SYNC_FIELD in DRA CheckChainLimit

[Xeeynamo]

As raised in #1723 (comment), we need to double-check if the field ext.weapon.equipId, previously known as ext.weapon.unkAE, needs to be sync across all the kind of weapon extensions. Syncing a field will involve the use of the macro utility SYNC_FIELD, which checks if two fields from two different structs match the same location in memory.