[CLI] Add functionality to change default system PHP version

[Edi Septriyanto]

Proposed command line syntax:

lemperctl stack config php --default-runtime=php@8.0

Add function to update default PHP version

RUNTIME=${1}

# Reserve default IFS
_IFS=${IFS}

IFS='@' read -r -a _RUNTIME <<< "${RUNTIME}"
PHP_VER_NUM="${_RUNTIME[1]}"

# Restore default IFS
IFS=${_IFS}

# Set the php version via update-alternatives

sudo update-alternatives --set php "$(command -v php${PHP_VER_NUM})"
sudo update-alternatives --set phar "$(command -v phar${PHP_VER_NUM})"
sudo update-alternatives --set phar.phar "$(command -v phar.phar${PHP_VER_NUM})"
sudo update-alternatives --set php-config "$(command -v php-config${PHP_VER_NUM})"
sudo update-alternatives --set phpize "$(command -v phpize${PHP_VER_NUM})"