TO add subscription command not defined correctly, doesn't accept hex MsgId

[skliper]

Describe the bug
Tried various settings to get a message limit of 4 (put 4 in each field) and none of them worked. Also doesn't accept 0x880 as a MsgId (seems to require base 10)

To Reproduce
Set MsgId of 0x880:

Traceback (most recent call last):
  File "/export/home/jhageman/cFS/cFS-GitHub/tools/cFS-GroundSystem/Subsystems/cmdGui/Parameter.py", line 68, in ProcessSendButton
    sendSuccess = self.mcu.sendPacket()
  File "/export/home/jhageman/cFS/cFS-GitHub/tools/cFS-GroundSystem/Subsystems/cmdGui/MiniCmdUtil.py", line 138, in sendPacket
    self.assemblePacket()
  File "/export/home/jhageman/cFS/cFS-GitHub/tools/cFS-GroundSystem/Subsystems/cmdGui/MiniCmdUtil.py", line 122, in assemblePacket
    priHeader = self.assemblePriHeader()
  File "/export/home/jhageman/cFS/cFS-GitHub/tools/cFS-GroundSystem/Subsystems/cmdGui/MiniCmdUtil.py", line 79, in assemblePriHeader
    self.assemblePayload()
  File "/export/home/jhageman/cFS/cFS-GitHub/tools/cFS-GroundSystem/Subsystems/cmdGui/MiniCmdUtil.py", line 92, in assemblePayload
    dataVal = int(items[1])
ValueError: invalid literal for int() with base 10: '0x880'

Tried with MsgId 2176, tried 4 in every field and TO didn't report a message limit of 4

Expected behavior
Accept hex MsgId, fields should work.

Code snips
TBD

System observed on:

• Hardware: cFS Dev Server
• OS: Ubuntu 18.04
• Versions: Bundle main

Additional context
Packet may update with nasa/to_lab#73

Reporter Info
Jacob Hageman - NASA/GSFC