Option to turn off Docker credential helper forwarding

[chrmarti]

          I added some comments on this issue here for the same problem: https://github.com/microsoft/vscode-remote-release/issues/7982

I am worried that this "automatic" behaviour will conflict with various setups, as this current feature has forced me to downgrade the extension. If possible, could this auto-adding of the cred store be feature toggled in devcontainer.json? My team have the container set up so that the container itself negotiates required authentication to services so even if there IS a credential helper on the host we do not want the container using it.

Originally posted by @finite8 in #8096 (comment)

[chrmarti]

This actually made it in with #7982 and is available in Dev Containers 0.278.0 and later: