Is your feature request related to a problem? Please describe.
One of the features that I use the most in this extension is the "Generate Interface Stubs" command. It's great, but one of my main gripes with the feature is having to actually remember both the package and name of the interface I am wanting to implement. Often I'll forget mid-typing, quit the prompt, go reference what I am trying to implement, return to my file, and then do the command again. Even more often I'll just mistype and nothing will be generated.

Describe the solution you'd like
It would be great to have a drop down list appear when you get to the interface name of the command. For instance:

When you type f *File and then space a drop down will appear with a list of packages, much like the list found in the "Add Import" command. You can then type the package name or choose from the list. After the dot, a list of all the interfaces found in that package will appear. You can then type the interface name or choose from the list.

Describe alternatives you've considered
Another idea would just be to check if the interface exists after every keystroke, and then give a warning if it does not. I think that this would feel bad since the extension would flash a warning to you every time you type.

Additional context
Example package selection

Example interface selection