Feature: Adds experimental Feature "Management Console"

[LordHepipud]

Adds new experimental feature Management Console for better and easier management for Icinga for Windows and improved automation and deployed.

In addition following changes were made:

• Added support to fetch network interface for Register-IcingaDirectorSelfServiceHost directly from provided director url
• Added support for Icinga Framework Code Cache file being deleted once the feature is disabled
• Added support to suppress any console output for the current PowerShell session by using Disable-IcingaFrameworkConsoleOutput and to enable it again by using Enable-IcingaFrameworkConsoleOutput
• Added support for -Release argument for Get-IcingaFrameworkServiceBinary suppressing questions and using GitHub as source directly if set
• Added support to color console output by using Write-IcingaConsolePlain with the new argument -ForeColor
• Added new feature to write Icinga for Windows console headers more easily, better structured and formatted with Write-IcingaConsoleHeader by adding line content as array elements
• Fixed possible crash on Get-IcingaAgentFeatures if PowerShell is not running as administrator and therefor the command icinga2 feature list can not be processed
• Fixed ConvertTo-IcingaSecureString to return $null for empty strings instead of throwing an exception