Use `conda run` to get the activated environment variables instead of activation using shell scripts

This is probably an oversight, looking at the code in EnvironmentActivationService.getActivatedEnvironmentVariablesImpl, we seem to be using conda shell activation scripts to run python code. I guess this needs to be changed to use conda run as well.

@brettcannon @karthiknadig /cc

[rchiodo]

With latest bits, I did the following:

• Create a new conda environment
• Ran a kernel from a conda environment
• Printed out sys.executable, sys.path, and os.environ to verify the correct environment was setup.

[rchiodo]

I don’t think there’s a good way to verify this other than to debug it.

This code path is used by jupyter to do things like start a kernel for a conda environment, so doing that would verify it isn’t broken.