fs-util: add racy RENAME_NOREPLACE fallback using access()

fs-util: add racy RENAME_NOREPLACE fallback using access()

Apparently FAT on some recent kernels can't do RENAME_NOREPLACE, and of
course cannot do linkat()/unlinkat() either (as the hard link concept
does not exist on FAT). Add a fallback using an explicit beforehand
faccessat() check. This sucks, but what we can do if the safe operations
are not available?

Fixes: #10063