Add .env file dialog should start from Run configuration working directory

[1oglop1]

Hi, thanks for the amazing plugin it helps a lot. There is one slight annoyance when enabling EnvFile in a run configuration, the dialogue window to search for the .env file starts in a last used directory. I think it would be much better (if possible) to start the search in Run Configuration working directory.

Expected flow:

1. Create Run Configuration, Set the working directory /my-run-configuration/directory/ (if not set, start at last known location)
2. Click EnvFile

3. Click Enable EnvFile
4. Click Add +
5. Click .env file or JSON/YAML file

6. Flie browser opens in working directory /my-run-configuration/directory/

[ashald]

I believe I had code to request the file dialog in the project directory. If that's not the case, or if that broke - I'd welcome a PR with a fix!