Fix writing hardlinks (#11340)

* don't use backup files with hardlinks

* check if the inodes remain the same in the test

* move funcs to faccess and use AsRawHandle

* use a copy as a backup for hardlinks

* delete backup after copy

Cargo.lock

@@ -1455,6 +1455,7 @@ dependencies = [
  "once_cell",
  "open",
  "pulldown-cmark",
+ "same-file",
  "serde",
  "serde_json",
  "signal-hook",