Load never completes if there are no manifests to process.

[brandon-reinhart]

0.1

This is a bit of a weird issue, but if you are using leafwing manifest's AssetLoadingState enum to advance a state machine (for example, a loading screen) and you have no manifests to load (for example, if they are commented out), you'll never advance past PROCESSING.

This is because if there are no manifests check_if_manifests_have_loaded advances, but check_if_manifests_are_processed depends on at least one manifest having called from_raw_manifest.