Support the metadata directory (as per PEP-517) for build_wheel #5587

Job	Run time
collateral (diffcov)	5m 23s
collateral (docs)	1m 57s
test (3.8, ubuntu-latest)	3m 49s
test (3.8, windows-latest)	13m 15s
test (3.13, ubuntu-latest)	4m 38s
test (3.13, macos-latest)	4m 58s
test (3.13, windows-latest)	9m 22s
test (3.9, ubuntu-latest)	3m 59s
test_cygwin (39, windows-latest)	13m 31s
test (3.10, ubuntu-latest)	3m 53s
test (3.11, ubuntu-latest)	4m 11s
test (3.12, ubuntu-latest)	4m 58s
test (3.14, ubuntu-latest)	4m 43s
test (pypy3.10, ubuntu-latest, stdlib)	12m 29s
test (ubuntu-latest, 3.10, stdlib)	3m 44s
test (3.8, macos-13)	8m 57s
integration-test	0s
check	4s
release	0s
	1h 43m 51s

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