[libc++][chrono] Add calendar type formatters.

Some of the calendar types have landed before, this adds the missing
set. Note this does not complete the implementation of the chrono
formatters.

This removes the `chrono` header for some transitive include in C++17
mode. This is needed to avoid inclusion cycles.

Partially implements:
- P1361 Integration of chrono with text formatting
- P2372 Fixing locale handling in chrono formatters

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D137022