Menu showcase improvements

I noticed that the menu showcase is very slow loading and, which is unexpected considered that it shouldn't depend on a lot of data.

A nice improvement would be to see the menu configuration file when expanding the code to see the full example directly in the showcase. An option would be to inline the content of that json file rather than importing it.

Locate the menu showcase entry point and its menu configuration JSON file, then inspect what data is loaded when the showcase renders and when the code example expands. Confirm the improvement by making the showcase load faster and showing the configuration content directly in the expanded example.

Written by the indexing model from the issue text.