[8.x] Remove an useless check in Console Application class

[seriquynh]

What I do?

I create this PR as a re-open PR of #40133

Why I do this?

@GrahamCampbell said I was incorrect but I was NOT incorrect.

1. If the condition ! isset($callingClass) && empty($parameters) is true, this line below will be executed and the $input will be an instance of StringInput.

$command = $this->getCommandName($input = new StringInput($command));

2. Otherwise, these two lines will be executed and the $input will be an instance of ArrayInput.

array_unshift($parameters, $command);

$input = new ArrayInput($parameters);

Conclusion

To conclude, there are no cases of this context in which the $input isn't set, it's always set. Therefore, the check $input ?? null is absolutely useless.

If the Laravel team rejects this PR, it will be your final decision and I understand. But rejecting this PR doesn't mean my PR is incorrect. It's reasonable.

Let's see the method more details:

protected function parseCommand($command, $parameters)
{
    if (is_subclass_of($command, SymfonyCommand::class)) {
        $callingClass = true;

        $command = $this->laravel->make($command)->getName();
    }

    if (! isset($callingClass) && empty($parameters)) {
        $command = $this->getCommandName($input = new StringInput($command));
    } else {
        array_unshift($parameters, $command);

        $input = new ArrayInput($parameters);
    }

    return [$command, $input ?? null];
}

[seriquynh]

@driesvints Could you take a look at this please!