Enhancement: Add support for toggling enabled state of deployment targets #311

The bug

It appears there is no support for toggling the enabled state of deployment targets.
The deployment target enable state could be set both upon deployment target creation and through a new deployment target update command.

Command to reproduce

octopus deployment-target azure-web-app create [flags]

Outcome

Deployment target enable with no facility to change the enabled state through the CLI.

Versions

2.1.0