Add OpenShift binaries to Dev Containers

[adambkaplan]

Dev Containers is a potentially powerful extension to VSCode. One of the neat features is that it lets you declaratively install extensions into a dev container.

The VSCode extension for Kubernetes seems to install kubectl onto the container, under /root/.local/state. The OpenShift extension doesn't seem to do this automatically for oc and other tools.

[datho7561]

Related is #2872. In fact, it seems that issue is a duplicate of this one

[mohitsuman]

@adambkaplan We have implemented this feature in the latest 1.5.0 release. Can you please try and let us know if it works as expected for you. Thanks.