[NEW] Add command completion support

[iXavierLiu]

# New Feature Request

• Is this feature related to an existing bug report?
  No

• What does this feature do?
  command completion

• Are there alternative solutions that already exist?
  see below

• Description
  I tried to use TAB to complete the command, but it displays the tab characters as is. I am not sure if the rcon protocol can support this, but I found a Linux package for rcon-completion.
  I have tried ARRCON briefly and it has performed well so far. If the command completion feature is supported by the rcon protocol, will you consider adding it to the subsequent development plan?