Disable parsing of VLAN-tagged frames (with TPID 0x8100)

This feature introduces an option to disable the parsing of the payload of Ethernet frames with Tag Protocol Identifier (TPID) 0x8100, which is used by VLAN-tagged frames. If you disable the parsing of frames with TPID 0x8100, then you cannot support tagged interfaces with the most common TPID 0x8100 on the router, which might be used as an additional security measure on core routers. The user can, however, configure other TPIDs as required.