SysEx: Split DigiTech commands dissection

Every SysEx Manufacturer can decide its own SysEx message format.
As there are quite a lot of registered SysEx Manufacturers, it is best
to not mix all the Manufacturer specific commands in one file.

During the extraction following have been changed:
  * sysex.digitech prefix changed to sysex_digitech
  * sysex.device_id changed to sysex_digitech.device_id as the MIDI
    System Exclusive specification doesn't specify anything except the
    (Extended) Manufacturer ID
  * sysex.digitech.device_id renamed to sysex_digitech.received_device_id
    as this field is part of the Who Am I command response
  * Remove the PROTO_CHECKSUM_ZERO flag - the actual checksum is simply
    XOR of all bytes. Prior this change the actual checksum byte was
    XORed together with the checksummed data.

Change-Id: I225149f16a83b7629ce4bf9f6ca81c1d93dd856a
Reviewed-on: https://code.wireshark.org/review/33070
Petri-Dish: Anders Broman <a.broman58@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

epan/dissectors/CMakeLists.txt

@@ -1741,6 +1741,7 @@ set(DISSECTOR_SRC
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-synphasor.c
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-sysdig-event.c
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-sysex.c
+	${CMAKE_CURRENT_SOURCE_DIR}/packet-sysex_digitech.c
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-syslog.c
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-t30.c
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-tacacs.c