Output CI version info to console

[jnm2]

I'm using Cake to pull the latest prerelease from the MyGet feed via #tool nuget:https://myget.org/f/nunit/?package=NUnit.ConsoleRunner&prerelease. I want the version to float, but I want to be able to know after the fact which MyGet build of NUnit Console was used in my CI builds. For example, the Cake script ran against 3.9.0-dev-04024 but I can't see that by reading my CI log:

NUnit Console Runner 3.9.0
Copyright (c) 2018 Charlie Poole, Rob Prouse

To fix this, can we have the AppVeyor CI build patch AssemblyInfo.cs with the current build number? I'd be happy to do it if you like the idea. (Where I work, we do AssemblyInfo.cs patching on projects where we can't move to the new SDK yet and pass an MSBuild property.)

Then, we'd replace this:

nunit-console/src/NUnitConsole/nunit3-console/Program.cs

Lines 161 to 164 in 3427b07

	private static void WriteHeader()
	{
	Assembly executingAssembly = Assembly.GetExecutingAssembly();
	string versionText = executingAssembly.GetName().Version.ToString(3);

With this:

string versionText = FileVersionInfo.GetVersionInfo(
    executingAssembly.ManifestModule.FullyQualifiedName).ProductVersion;

[ChrisMaddock]

Fine by me!