Command tab completion no longer works when a command does not start with /

[Felanbird]

Steps to replicate:

1. Make a command
2. Set the trigger to anything that doesn't start with / ( e.g command )
3. Attempt to use tab-completion to complete the command
4. guh
5. Notice that once failing to tab complete the command, tab completion with a / works, despite the command not having a /

almost certainly caused by #4639

originally reported in discord: https://discord.com/channels/253897423439659008/459650160658481152/1156813105528061992

[Mm2PL]

https://github.com/Chatterino/chatterino2/pull/4639/files#diff-a1f6c3a68ede506e1729224bde149ba0014e9cf11d55315eecb63a3119bcc5aaR75-R78

[Felanbird]

Unlucky but we definitely can't do that, since we have both #3583 and #4233 - both of which use commands as their workaround.

[Mm2PL]

Yeah, tab completion needs to go back to querying everything or most things for this to work.

[dnsge]

If I'm understanding the original behavior, it should be trivial to fix:

chatterino2/src/controllers/completion/sources/UnifiedSource.cpp

Lines 18 to 19 in 783c753

	this->emoteSource_.update(query);
	this->usersSource_.update(query);

can be updated to also use the command source.

I'll do some tinkering to see if this restores the original behavior.