Implement zoneinfo parsing/compilation and add TZif structs #886

Job	Run time
MSRV	26s
Lint	21s
Test (stable, ubuntu-latest)	22s
Test feature matrix	2m 35s
Test (stable, macos-latest)	26s
Test (stable, windows-latest)	2m 29s
Documentation	26s
Test FFI (stable, ubuntu-latest)	39s
	7m 44s

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