Install globally with --user

• I have searched the issues of this repo and believe that this is not a duplicate.
• I have searched the documentation and believe that my question is not covered.

Feature Request

I am using Poetry to install project dependencies into a Docker container where I do not have root access. Since using a virtualenv would be unnecessary (there is only ever one project in this container) and a waste of time (this is done as part of a web service aiming at speed), I configure settings.virtualenvs.create to false. However, this causes Poetry to try to install the packages system-globally, which fails because I don't have root access in the container.

I would like a way to tell Poetry to use pip install --user instead of just pip install to install packages when virtualenvs are disabled.