Make tabs on the resource show page lazy-loaded

[aine-etke]

For example, when you have a user who actively used matrix, uploads media, participates in plenty of rooms, etc.
When you try to open that user's show page, it takes a lot of time, even the browser suggests stopping the page, as it slows the browser down.

I already attempted to make that using React.lazy with Suspense wrapping the tab content, but that didn't help - requests to load rooms, media, etc. were sent (and processed).

An alternative (temporary workaround) approach could be wrapping tabs' datagrids in List to limit the number of entries to 10. Unfortunately, I failed to make this work either because I didn't figure out how to wire it with Reference fields (heavily used)