Update the bot relay

[negativeeddy]

This update contains the following changes

• adds an ARM template and "deploy to Azure" button for the Azure Relay
• .NET Core project
  • updated to .NET 5.0
  • converted to generic .NET hosting service this will also allow using web API to be used for callbacks to get bidirectional support
  • supports command line parameters for easy launching instead of changing appsettings.json
  • fixed a bug where it crashed when the OPTIONS request came through
• updated docs