Fix routing of unsupported MEI types

[MrAlaskan]

Summary

Prevent unsupported Encapsulated Interface Transport (FC 0x2B) MEI types from being routed to the Read Device Identification implementation.

Problem

Function code 0x2B uses the MEI Type field to dispatch requests to different encapsulated interfaces. Read Device Identification is specifically assigned MEI type 0x0E, while 0x0D represents the separately defined CANopen General Reference interface and other ranges are reserved.

Previously, ReadDeviceInformationRequest was registered as both the base handler for function 0x2B and the handler for MEI type 0x0E. When the decoder received another MEI type and could not find a matching subtype, it retained the base ReadDeviceInformationRequest object. The server could consequently process an unsupported or reserved MEI request as Read Device Identification and return a normal 0x0E response with semantics unrelated to the original request.

Changes

This change introduces a generic Encapsulated Interface Transport dispatch PDU as the base handler for function 0x2B. MEI type 0x0E continues to route to ReadDeviceInformationRequest, while unsupported and reserved MEI types remain on the generic handler and return ILLEGAL_FUNCTION (0x01) instead of entering the device-identification logic.

Tests verify that 0x0E still routes correctly and that MEI types 0x00, 0x0D, 0x0F, and 0xFF are not interpreted as Read Device Identification requests and return the expected exception.

[janiversen]

LGTM, thanks.