Features: Set USERNAME to _REMOTE_USER if available

[Samruddhi Khandale (samruddhikhandale)]

Helps fix #307

[John Keech (jkeech)]

Can you please add some test cases that verify the features work properly for non-standard remoteUsers?

[Samruddhi Khandale (samruddhikhandale)]

Can you please add some test cases that verify the features work properly for non-standard remoteUsers?

For node, I tired adding a test-scenario as follows

    "test_non_root_user": {
        "image": "ubuntu:focal",
        "features": {
            "common-utils": {
                "username": "app"
            },
            "node": {
                "version": "19.1.0"
            }
        }
    }

However, even before the changes in the PR, the tests pass. The nvm folder is set with correct user permissions & node is installed fine.

I thought of repro-ing the scenario using dockerfile which creates this user, however the features test command doesn't support that. Need to fix that. // cc - joshspicer

John Keech (@jkeech) Not sure how else I could write tests 😕

[Samruddhi Khandale (samruddhikhandale)]

Closing this in favor of #264