Add command line exception

Author: viningtechsola

src/TfvcMigrator/CommandLineException.cs

@@ -0,0 +1,9 @@
+namespace TfvcMigrator;
+public sealed class CommandLineException : ApplicationException
+{
+    public int ExitCode { get; }
+    public CommandLineException(string message, int exitCode = 1) : base(message)
+    {
+        ExitCode = exitCode;
+    }
+}