Write available commands on CLI help command

resolves https://github.com/abpframework/abp/issues/1186

framework/src/Volo.Abp.Cli.Core/Volo/Abp/Cli/Commands/HelpCommand.cs

@@ -1,6 +1,8 @@
-using System.Threading.Tasks;
+using System.Linq;
+using System.Threading.Tasks;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
 using Volo.Abp.Cli.Args;
 using Volo.Abp.DependencyInjection;
 
@@ -9,10 +11,12 @@ namespace Volo.Abp.Cli.Commands
     public class HelpCommand : IConsoleCommand, ITransientDependency
     {
         public ILogger<HelpCommand> Logger { get; set; }
+        protected CliOptions CliOptions { get; }
 
-        public HelpCommand()
+        public HelpCommand(IOptions<CliOptions> cliOptions)
         {
             Logger = NullLogger<HelpCommand>.Instance;
+            CliOptions = cliOptions.Value;
         }
 
         public Task ExecuteAsync(CommandLineArgs commandLineArgs)
@@ -20,10 +24,16 @@ namespace Volo.Abp.Cli.Commands
             Logger.LogInformation("");
             Logger.LogInformation("Usage:");
             Logger.LogInformation("");
-            Logger.LogInformation("  abp <command> <target> [options]");
+            Logger.LogInformation("    abp <command> <target> [options]");
             Logger.LogInformation("");
+            Logger.LogInformation("Command List:");
 
-            //TODO: Write available commands (not hard-coded, but from the CliOptions.Commands)
+            foreach (var commandKey in CliOptions.Commands.Keys.ToArray())
+            {
+                Logger.LogInformation("    " + commandKey);
+            }
+
+            Logger.LogInformation("");
 
             return Task.CompletedTask;
         }