REGRESSION: Fix console command completion help

[dhthwy]

Console command completion help was inadvertently broken in a prior commit. This PR should resolve the issue. Tested on posix console.

This could probably use a test, if I can figure out a proper way to do it.

[lethosor]

works on my end too

[lethosor]

This actually would not be that hard to test from Lua:

[lua]# ~dfhack.internal.runCommand('autodum')[1]
table: 0x7fff98822d50
1                        = 12
2                        = autodum is not recognized. Possible completions: autodump autodump-destroy-here autodump-destroy-item

but I'm not sure how to best make it robust to new tools being added, because the current logic gives no completions if there are too many possibilities:

[lua]# ~dfhack.internal.runCommand('aut')[1]
table: 0x7fff985387d0
1                        = 12
2                        = aut is not a recognized command.

[quietust]

Looks like this broke way back in 2022 with commit e926e11.

[dhthwy]

if helpdb handled command aliases we could make some nonsense alias to a command and do it that way. Otherwise we'd have to construct a new one - and I don't know how to do that in a test.

There aren't that many commands, the limit of 8 should be much higher. Maybe even no limit provided that the list of possibles isn't the full command set.