Support for custom dynamic help option for a single subcommand?

For all my current subcommands I am using the default help option (which is very nice btw!). I have 1 subcommand that I want the default help options to be turned off for so that I can display custom help code inside of my subcommand's OnExecute method:

```
protected bool HandleHelp(){
//TO DO: Check to see if --help was passed in and display custom help text to the console based on a Dictionary of known commands on current machine.
}
protected override async Task OnExecute(CommandLineApplication app)
{
try
{
//Load a list of all the available commands
BuildListOfKnownCommands();

//Check for help option and display help message for specific tool
if(HandleHelp()){
return 0;
}

//TO DO: Run command
return 0;
}
catch (Exception ex)
{
OnException(ex);
return 1;
}
```

Is there an easy way to do this?

I have tried adding a member to my subcommand like so:

```
[HelpOption("--help")]
public bool HelpRequested {get;set;} = false;
```

but this gives me the error message **"Multiple HelpOptionAttributes found. HelpOptionAttribute should only be used one per type, either on one property or type."**

I tried using the attribute `[SuppressDefaultHelpOption]` to disable the default --help behavior but that didn't seem to take.

My subcommand has the following options:

```
[Command(Name = "tools", OptionsComparison = StringComparison.InvariantCultureIgnoreCase, Description = "Run helpful developer tools and scripts")]
[SuppressDefaultHelpOption]
```

Can the default --help behavior be turned off for just a single subcommand so that I can do my own custom dynamic --help function?

Thanks!

Beginne damit nachzuverfolgen, wie HelpOptionAttribute und SuppressDefaultHelpOption auf einen Unterbefehl angewendet werden, bevor OnExecute ausgeführt wird. Reproduziere den im Issue beschriebenen Fall mit einem einzelnen Unterbefehl und verifiziere anschließend, dass sich das standardmäßige --help-Verhalten für diesen Unterbefehl deaktivieren lässt, während es für andere Unterbefehle erhalten bleibt und eine benutzerdefinierte Behandlung in OnExecute ausgeführt werden kann.

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