`asset_server.load_folder` never creates a `LoadedFolder` asset if _any_ asset contained errors while loading

## Bevy version

0.12.0

## What you did

Had a typo in a ron custom asset such that `ron::de::from_bytes(&bytes)?` returned an error

## What went wrong

- what were you expecting?
`LoadedFolder` asset would show up with most handles being in `LoadState::Loaded` and the one typo resulting in a `LoadState::Failed`
Error messages would be output from failed load(s)

- what actually happened?
`LoadedFolder` asset for the folder containing one broken asset and many valid assets was never created
No errors are sent to the console

## Additional information

I also noticed that `LoadedFolder` assets aren't created until all handles within them have completely reached `LoadState::Loaded` even when everything is going correctly, so you can't check for the progress of the individual assets being loaded. Seems related, but at the very least I think it needs to be created when all handles reach either `LoadState::Loaded || LoadState::Failed`

Start at asset_server.load_folder and trace how LoadedFolder creation handles child LoadState values. Reproduce the case with a custom RON asset containing a deserialization error and several valid assets; done means the folder asset is created when children reach Loaded or Failed, failed-load errors are reported, and individual loading progress remains observable.

Written by the indexing model from the issue text.