ObjectStore Soft Delete Support

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

Many object stores support some notion of versioning and/or generations. Additionally some, such as Azure Blob Storage, have a specialized notion of [soft deletion](https://learn.microsoft.com/en-us/azure/storage/blobs/soft-delete-blob-overview).

Full support for generations is likely out of scope not least because:

* It is unclear how to support versioning for `LocalFileSystem` whilst preserving atomicity
* The stores are not very consistent in how upserts/deletes interact with versions
* I lack a motivating use-case to guide the API design

**Describe the solution you'd like**

I would like a new method

```
/// Restore a previously deleted object if possible
///
/// Returns
/// - Error::AlreadyExists if the object is not deleted
/// - Error::NotFound if no soft deleted version can be restored
fn restore(&self, path: &Path) -> Result<()> {
Err(Error::NotImplemented)
}
```

**Describe alternatives you've considered**

We could not do this

**Additional context**

Start by reviewing the object-store API and its implementations, especially LocalFileSystem, against the proposed restore(path) contract. Define how soft-deleted objects are detected and restored across supported stores, including the stated AlreadyExists and NotFound outcomes; done means the API behavior and implementation scope are agreed and covered appropriately.

Written by the indexing model from the issue text.