Run Rust library test suite as well as integration tests

[cormacrelf]

• Add cargo test --lib to CI
• Make all the lib tests run (not pass)
• Filter date-parts correctly when producing sort strings
• Finally fix flipflop_Apostrophes.txt and pass all the io tests

Now all the tests do pass, and one new passing integration test came out of it.

[cormacrelf]

improved: csl_test_suite::flipflop_Apostrophes.txt
test result: 0 regressions, 1 new passing tests, 0 new ignores, 0 outputs changed, out of 887 intersecting tests
blessed: 821 passed; 42 failed; 24 ignored
current: 822 passed; 41 failed; 24 ignored