Feature: #99341 - Introduce CLI create user command

Description

A new CLI command backend:user:create, which automates backend user creation, is introduced as an alternative to the existing backend module.

Impact

You can now use ./bin/typo3 backend:user:create to create a backend user without touching the GUI.

Example

Interactive / guided setup (questions/answers):

./bin/typo3 backend:user:create

User creation using environment variables:

TYPO3_BE_USER_NAME=username \
TYPO3_BE_USER_EMAIL=admin@example.com \
TYPO3_BE_USER_GROUPS=<comma-separated-list-of-group-ids> \
TYPO3_BE_USER_ADMIN=0 \
TYPO3_BE_USER_MAINTAINER=0 \
./bin/typo3 backend:user:create --no-interaction

Warning

Variable TYPO3_BE_USER_PASSWORD and options -p or --password can be used to provide a password. Using this can be a security risk since the password may end up in shell history files. Prefer the interactive mode. Additionally, writing a command to shell history can be suppressed by prefixing the command with a space when using bash or zsh.