User name auto complete on certain commands

[nD00rn]

Describe the pull request

Certain commands in the Twitch chat require a user name to be entered
after the command. This PR enforces the auto completion to only
suggest user names and not to suggest any of the available emotes for
the user when providing the first argument.

This feature will work for the following commands at this moment of
writing.

/ban
/block
/mod
/purge
/timeout
/unban
/unblock
/unmod
/untimeout
/unvip
/user
/vip
/w

Why

This prevents the user from entering an emote instead a username when
for example trying to ban someone.

How

Whenever the 'tab' key is pressed it checks if the one of the previous mentioned commands is typed in, next it checks if the word the user currently is typing is the first argument after the command. If this first argument check was not in place the user would not be able to auto complete any available emote.

The commands which are processed like this are described in the Commands.ts found in the constants folder. In the command description it states if a username is an argument or not.

[HiDeoo]

Thanks for the pull request. I slightly refactored the code:

• There was way too much possible iterations for such a feature.
• All the code was executed at every completion attempt while we can often bail out early.
• There was an issue when you were trying to autocomplete the username while the second argument of the command was already given.

(I also updated the changelog 👍)