repository: Push all usage of errors.Fatal out of the package

As the `Fatal` error type only includes a string, it becomes impossible
to inspect the contained error. This is for a example a problem for the
fuse implementation, which must be able to detect context.Canceled
errors.

Co-authored-by: greatroar <61184462+greatroar@users.noreply.github.com>

cmd/restic/cmd_init.go

@@ -93,7 +93,7 @@ func runInit(ctx context.Context, opts InitOptions, gopts GlobalOptions, args []
 		PackSize:    gopts.PackSize * 1024 * 1024,
 	})
 	if err != nil {
-		return err
+		return errors.Fatal(err.Error())
 	}
 
 	err = s.Init(ctx, version, gopts.password, chunkerPolynomial)