CD - Add Annotations on metric charts with Application Insights

[mathieu-benoit]

Since Azure PowerShell v5.0.0 - https://github.com/Azure/azure-powershell/releases/tag/v5.0.0-November2017 - we are now able to automatically generate API Key (New-AzureRmApplicationInsightsApiKey) to be able to integrate Annotations on metric charts with Application Insights during the CD pipeline: https://docs.microsoft.com/en-us/azure/application-insights/app-insights-annotations

TODO: need to check the version of Azure PowerShell on VSTS agent used - https://docs.microsoft.com/en-us/vsts/build-release/concepts/agents/hosted