Refactor the `features` module (#2592) #1654

Job	Run time
docs	37s
msrv	2m 2s
rustfmt-clippy	43s
check-cfg	33s
minimal	16s
quickchecking	26s
test (ubuntu-latest, 5.0, 1, 0, 0, 0, 0)	2m 24s
test (ubuntu-latest, 5.0, 1, 0, 0, 1, 0)	3m 6s
test (ubuntu-latest, 5.0, 1, 0, 1, 0, 0)	2m 26s
test (ubuntu-latest, 5.0, 1, 0, 1, 1, 0)	3m 41s
test (ubuntu-latest, 5.0, 1, 1, 0, 0, 0)	3m 23s
test (ubuntu-latest, 5.0, 1, 1, 0, 1, 0)	4m 32s
test (ubuntu-latest, 5.0, 1, 1, 1, 0, 0)	4m 9s
test (ubuntu-latest, 5.0, 1, 1, 1, 1, 0)	3m 28s
test (ubuntu-latest, 9.0, 1, 0, 0, 0, 0)	3m 45s
test (ubuntu-latest, 9.0, 1, 0, 0, 1, 0)	3m 30s
test (ubuntu-latest, 9.0, 1, 0, 1, 0, 0)	2m 54s
test (ubuntu-latest, 9.0, 1, 0, 1, 1, 0)	3m 13s
test (ubuntu-latest, 9.0, 1, 1, 0, 0, 0)	5m 30s
test (ubuntu-latest, 9.0, 1, 1, 0, 1, 0)	3m 50s
test (ubuntu-latest, 9.0, 1, 1, 1, 0, 0)	3m 47s
test (ubuntu-latest, 9.0, 1, 1, 1, 1, 0)	4m 56s
test (ubuntu-latest, 9.0, 0, 0, 1)	1m 36s
test (macos-latest, 9.0, 0, 0, 0)	2m 16s
test-book	11s
test-expectations (ubuntu-latest)	1m 34s
test-expectations (macos-latest)	3m 45s
	1h 12m 33s

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