The workspaces seem to come with nvm and rvm installed. Perhaps https://github.com/phpbrew/phpbrew should be installed as well. It is the leader in the equivalents among PHP as far as I can tell.
Anyway, I just installed phpbrew. Just follow the instructions:
curl -L -O https://github.com/phpbrew/phpbrew/raw/master/phpbrew
chmod +x phpbrew
sudo mv phpbrew /usr/local/bin/phpbrew
I used sudo -s to create a new shell and do it because I’m still new to this, but it seems like you’re given root privileges anyway so that may not be necessary.