[Feature] An option to start only ssh server inside SageMaker Studio

[ivan-khvostishkov]

Now SageMaker SSH Helper starts VNC server and Jupyter server along with sshd. The new option will allow to start only the minimal necessary service sshd. The user will need to comment the second line in the IDE notebook cell and uncomment the third one:

sm-ssh-ide stop
sm-ssh-ide start
#sm-ssh-ide start --ssh-only

[ivan-khvostishkov]

Added the flag --ssh-only both to sm-ssh-ide start and sm-local-ssh-ide connect commands.