Switch to the new granular format_functions header. Since the chrono's
format dependency in C++20 hasn't been in a release it's save to remove
it.
Depends on D133665
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D133796
#include <__chrono/day.h>
#include <__chrono/statically_widen.h>
#include <__config>
-#include <format>
+#include <__format/format_functions.h>
#include <ostream>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
cwchar
cwctype
exception
-format
functional
initializer_list
ios
cwchar
cwctype
exception
-format
initializer_list
ios
iosfwd