Block the start of an environment deploy/app if the agent is disconnected

[afjsilva]

Was added code to call a new API CanStartDeploymentConnection() to check the agent connection status before start the deployment of an environment or app. When a deploymentTarget is remote, the API call occurs. If the depoyment can't start because the connection is not possible, an exception is throw.
This validation is for new environment deployments or apps.

[EgzysT]

"Creating new environment" log should probably only be shown after the checking the infra agent connection, to avoid showing that log if the connection fails

[afjsilva]

Creating new environment

Please check now :) Thx!