Add deployment: allow specifying deployment key

[grav]

When migrating an existing app to the stand-alone server, it makes sense to re-use existing deployment keys.

The Rest API already allows for explicitly specifying deployment key, so this PR just adds an optional argument to the deployment add command.

Example usage:

code-push-standalone deployment add my-app prod existing-key-abc123

[grav]

@microsoft-github-policy-service agree

[amdrade]

+1

[DmitriyKirakosyan]

@grav Thank you for your contribution! I’ve tested your changes, and they work as expected. Could you please update the documentation and the command description to reflect the newly added argument?

[grav]

@DmitriyKirakosyan Thanks for the feedback. I've added example usage to the CLI configuration and the README.

[lucen-ms]

Thank you @grav for your contribution.