Reserved token length responds with incorrect message ID (confirmable)

[gdstirling]

Confirmable messages that have an invalid token length (ie >8) do not respond with a valid message code. It's due to this error handling happening before message ID is stripped out of the header.

Header error handling should probably all be moved down to after header is decoded.

if (TokenLength > 8) {
		INFO("CoAP-Parse Byte1 Error\r\n");
		return COAP_PARSE_MESSAGE_FORMAT_ERROR;
	} // return COAP_PARSE_MESSAGE_FORMAT_ERROR;