[ticket/12655] Run phpbbcli as a shell when --shell or -s is used
* Nicofuma/ticket/12655:
[ticket/12655] Set register_container_commands as public
[ticket/12655] Don't try to restore the definition in the help
[ticket/12655] Fix coding style
[ticket/12655] Make the --shell option available only for phpbbcli.php
[ticket/12655] Fix coding style in \phpbb\console\application
[ticket/12655] Set the arguments of \phpbb\console\application as required
[ticket/12655] Don't require acp/common again in the commands
[ticket/12655] Run the shell when --shell is used