Suggestion: Add create-command-object to the Grails CLI

### Suggestion
- Add create-command-object to the Grails CLI
### Why?

For example with IntelliJ, when you create a new file/class it gets automatically saved and loaded by Spring Loader. As a command object needs to implement the Validateable interface and Spring Loaded does not support reloading interfaces this cause some issues. You either need to rename the class or restart your development application.

Example:

```
Spring Loaded: Cannot reload new version of com.example.person.UpdatePersonForm
Reason: Interfaces changed from [groovy/lang/GroovyObject] to [grails/validation/Validateable, grails/validation/Validateable$Trait$FieldHelper, groovy/lang/GroovyObject]
```

This could be avoided by using the create-command-object command which uses a template. Also maybe command objects could get their own folder like domain-classes, controllers and taglibs?

I would love to hear what other people think about this.

No files or tests are named. Start by inspecting the existing Grails CLI create commands and their templates, then compare how domain classes, controllers, and taglibs choose generated locations. Done means a create-command-object command generates a command object implementing Validateable and establishes its intended folder placement.

Written by the indexing model from the issue text.