[ticket/12685] New CLI container for load extensions

https://tracker.phpbb.com/browse/PHPBB3-12685

PHPBB3-12685
One solution is to override getDefaultInputDefinition() in \phpbb\console\application like this:
```
	protected function getDefaultInputDefinition()
	{
		$input_definition = parent::getDefaultInputDefinition();
		$input_definition->addOption(new InputOption(
			'safe-mode',
			null,
			InputOption::VALUE_NONE,
			$this->user->lang('CLI_DESCRIPTION_OPTION_SAFE_MODE')
		));

		return $input_definition;
	}
```
But this way you also have to change the constructor (the call to the parent needs to be the last instruction). And off course you revert the changes made to getHelp