Test discovery and runner should use the test config

[karthiknadig]

Suppose I have a module that i am including via pythonpath. Currently i can debug that by passing env via debug configuration. I should be able to provide similar configuration for tests.

        {
            "name": "Test Config",
            "type": "python",
            "request": "test",
            "env":{
                "PYTHONPATH": "${workspaceFolder}/mymodule"
            }
        }

With this folder structure:

You can run or debug. But test discovery/running does not work.,

[DonJayamanne]

The test discovery and runner should already use the .env file.
If not this is a regression, there's a similar issue that I'm tracking (triaging), possibly related and possibly a regression (not using .env files when discovering and running tests).

[DonJayamanne]

Duplicate of #7581
Related to PYTHONPATH in env variables