unpack_strategy/directory: use mv for nested unpack #30829

Job	Run time
syntax	48s
vendored gems	57s
formula audit	4m 23s
cask audit	2m 23s
tap syntax	6m 28s
test default formula (Ubuntu 22.04)	1m 28s
tests (online)	2m 59s
test default formula (Ubuntu 20.04)	2m 50s
update-test (Ubuntu 22.04)	25s
tests (generic OS)	2m 45s
test default formula (macOS 13 x86_64)	3m 14s
update-test (macOS)	24s
tests (Ubuntu 22.04)	3m 1s
test default formula (macOS 15 arm64)	1m 15s
tests (Ubuntu 20.04)	3m 1s
tests (macOS 13 x86_64)	3m 0s
tests (macOS 15 arm64)	3m 1s
	42m 22s

Provide feedback