Add commands for deployment targets

[dexyk]

Commands to support the management of the deployment targets:

• create - to create a new target
• edit - to update existing target, activate/deactivate it
• get - to list targets for a project, or describe a specific target given its id or name + project id combination, or provide a history of deployments for a deployment target
• delete - to delete a target

[DamjanBecirovic]

/sem-approve

[DamjanBecirovic]

Please add cmd/create_target_test.go file with tests for sem create deployment_target ... command.
You can use cmd/create_secret_test.go as a reference.

[DamjanBecirovic]

/sem-approve

[DamjanBecirovic]

/sem-approve

[DamjanBecirovic]

/sem-approve