Modernize solution, fix package symbol upload

[Arkatufus]

Changes

• Modernize solution
  • Replace common.props with Directory.Build.props
  • Add Directory.Packages.props
  • Replace Serilog.Sink.ColoredConsole with Serilog.Sink.Console (deprecated)
• Fix Fake and AzDo script
  • Add nuget package upload retry mechanism
  • Make sure that nuget API key are not leaked via build output
  • Remove symbolpublishurl parameter, this should be inferred from the service discovery URL, not baked in.
  • Add default publish source URI, defaults to http://api.nuget.org/v3/index.json
  • Change AzDo nugetpublishurl parameter to point to the service discovery URL instead of the package upload URL

[Arkatufus]

The last item is the actual fix, but I might as well fix the Fake script and modernize the whole solution.
Tested using local baget installation, works just fine.

Starting Target: PublishNuget (==> SignPackages)
Pushing nuget packages
Pushing D:\git\akkadotnet\Akka.Logger.Serilog\bin\nuget\Akka.Logger.Serilog.1.5.12.nupkg Attempts left: 3
Pushing Akka.Logger.Serilog.1.5.12.nupkg to 'https://localhost:5001/api/v2/package'...
  PUT https://localhost:5001/api/v2/package/
  Created https://localhost:5001/api/v2/package/ 615ms
Your package was pushed.
Pushing Akka.Logger.Serilog.1.5.12.snupkg to 'https://localhost:5001/api/v2/symbol'...
  PUT https://localhost:5001/api/v2/symbol/
  Created https://localhost:5001/api/v2/symbol/ 122ms
Your package was pushed.
Finished Target: PublishNuget

[Aaronontheweb]

LGTM