Add example module

[sudara]

I'm thinking of adding the inspector by default.

It could also just be commented out in CMake, making it really easy to uncomment to add.

A main benefit is to show new CMake users an example of how modules should be setup.

[sudara]

@chrhaase Do you have any opinions on this?

[chrhaase]

Good idea! Would you then add the inspector to the editor as well? I'm thinking if it's an optional thing, it's probably cleanest to do it with FetchContent instead of a submodule?