mv,cp: fix xattr TOCTOU by using file descriptor-based operations #18159

Job	Run time
Build and test uufuzz examples	1m 42s
Build the fuzzers	2m 57s
Fuzz (fuzz_cut, false)	1m 8s
Fuzz (fuzz_parse_size, false)	1m 19s
Fuzz (fuzz_printf, true)	1m 58s
Fuzz (fuzz_parse_glob, true)	2m 6s
Fuzz (fuzz_parse_time, false)	3m 22s
Fuzz (fuzz_sort, false)	2m 49s
Fuzz (fuzz_wc, false)	1m 14s
Fuzz (fuzz_seq_parse_number, false)	1m 10s
Fuzz (fuzz_echo, true)	3m 47s
Fuzz (fuzz_tr, false)	2m 53s
Fuzz (fuzz_cksum, false)	2m 59s
Fuzz (fuzz_expr, true)	2m 14s
Fuzz (fuzz_split, false)	1m 45s
Fuzz (fuzz_dirname, true)	3m 35s
Fuzz (fuzz_env, false)	2m 47s
Fuzz (fuzz_non_utf8_paths, true)	4m 12s
Fuzz (fuzz_seq, false)	1m 15s
Fuzz (fuzz_date, true)	2m 20s
Fuzz (fuzz_test, true)	3m 50s
Fuzzing Summary	6s
	51m 28s

Provide feedback