[Naming] review demo projects names

@addyosmani
I think `device-class aware loading` should be renamed to `device-class aware code-splitting`.
I think we might need to rename like `resource loading`, `code-splitting`, `data-fetching`. That is, just `loading` → `resource loading` since I think it sounds like loading covers more range including `resource loading`.

`cra-memory-considerate-loading` -> `cra-memory-considerate-code-splitting` or `cra-memory-considerate-resource-loading` because both mode are used here.

FYI: I found this issue while writing `Recipes` section in hooks/README.