Resources that are created via the normal Component-path API place IsResource on the Data Entity

## Bevy version and features

Main

## What you did

Was thinking through an expansion to the design of Resources as Components.
Discord: https://discord.com/channels/691052431525675048/749335865876021248/1548528942967947375

## What went wrong

`IsResource` is an Required Component for Resources, which means it gets added/inserted onto whatever Entity the Resource is, which for the expected Resource-path API is sound/correct, but when using the normal Component-path API then `IsResource` will end up on the Data Entity rather then the Component/Resource Entity. (The Component/Resource Entity also ceases to exist as well)

## Additional information

`world.spawn(MyResource)` - Data Entity: MyResource, IsResource
vs
`world.init_resource::()` - Component/Resource Entity: MyResource, IsResource

I'm honestly not sure if you would consider this a bug, because technically Components as Entities hasn't happened yet, so the Resource Entity is and isn't one. I would assume though, since the Components as Entities path is almost guaranteed at this point that this is indeed a bug, but maybe cant be fixed till Components as Entities proper.

Start by reproducing the difference between world.spawn(MyResource) and world.init_resource::() and trace how each API handles the Data Entity and Component/Resource Entity. Read the resource and required-component paths involved, then define and test the expected IsResource placement once Components as Entities support is considered complete.

Written by the indexing model from the issue text.