LocalFileSystem Copy is not Atomic

[chebbyChefNEQ]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

In most object stores copy operation is atomic, the file will not appear partially written.

However, on *nix, copy is usually not atomic and partially written file can appear.

Describe the solution you'd like

It would be nice if object_store had a atomic_copy api

Describe alternatives you've considered

I have been doing

store.copy(source, staging_file).await?;
store.rename(staging_file, dest).await?;

[tustvold]

This is actually a bug, ObjectStore operations should be atomic except for where explicitly stated otherwise (append)

[tustvold]

label_issue.py automatically added labels {'object-store'} from #4759