Add support for "Create Module" as a directory instead of a file

Right now, I can use the awesome "Create Module" on the lightbulb menu to create a module from just the mod xyz; statement. However, this always creates it as a file and not as a directory.

It would be really useful if it were able to do both - probably as separate menu items - for the cases where you actually do want to create a directory for the module instead of just a single file.

Reproduction

• Write mod xyz;
• Click Lightbulb
• Click "create module"

Current Behaviour

• A new file "xyz.rs" will be created adjacent to this file

Desired Behaviour

• A new directory "xyz" will be created adjacent to this file
• A new file "mod.rs" will be created inside this new directory

Reproduce the issue from a mod xyz; statement through the Lightbulb menu's "Create Module" action. Trace that action's entry point and verify how it chooses the generated path. Done means the existing file behavior remains available and a directory xyz containing mod.rs can be created adjacent to the source file.