Support altering project-level environment variables with `gp env`

[axonasif]

Is your feature request related to a problem? Please describe

Right now gp env can only alter the user-level environment variables. That means, if you try to add a var like so: gp env foo=bar, it will get registered under your personal account but not project. Similarly, it will only list your user vars when gp env is run.

Describe the behaviour you'd like

Add a CLI flag to specify the target, either user or current project.

Describe alternatives you've considered

Additional context

Front conversations

[geropl]

@akosyakov gp is owned by Team IDE, right?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[axonasif]

not stale 😄