It disables entire branch of tests declaration unconditionally because CXX_STANDARD
is not defined there. But even we use CMAKE_CXX_STANDARD here, these tests should
not be disabled with standard >= C++20.

* Don't explicitly delete copy ctor of dynamic_format_arg_store

Explicitly deleting the copy ctor causes the move constructor to not be
implicitly generated. This behaviour is different than what was in
v8.0.1 and causes code that relied on the move ctor of
dynamic_format_arg_store to break.

* Add test for dynamic_format_arg_store's move ctor

* include <memory>, don't use make_unique

Signed-off-by: Stefan Weil <sw@weilnetz.de>

works only if all named arguments are UDL-based

* Add support for subsecond printing for std::chrono::duration according to the c++20 standard

* Remove assert test that overflows intmax_t

* * Hopefully fix int64_t to int32_t conversion errors.
* Allow proper Duration::rep type to propagate via template argument deduction

* * Hopefully fix int64_t to int32_t conversion errors.
* Allow proper Duration::rep type to propagate via template argument deduction

* Fix sign conversion (-Wsign-conversion) warning treated as error in num_digits()

* Format chrono.h with clang-format

* Remove extra forward slash in doxygen style comment
Co-authored-by: Victor Zverovich <victor.zverovich@gmail.com>

* Apply all suggestions from GitHub, except for replacing the utility subsecond_helper class with a function

* * Move logic of handling subseconds from utility class to function with name write_fractional_seconds()
* Revert write(Rep value, int width) function to previous state

* Fix -Wshadow warning

* Remove unsued get_subseconds() function, its logic has been moved to write_fractional_seconds()

* Change comment from lowercase int to uppercase Int

* Simplify test check

* Integrate suggested changes

* Remove static from detail functions, they are no longer member functions of a class and static is unnecessary.
* Change comment from "amount" to "number"
Co-authored-by: Victor Zverovich <victor.zverovich@gmail.com>

* Move fmt::detail::formatbuf to format.h

* Replace std::basic_ostringstream to std::basic_ostream with custom formatbuf

* Use tm.tm_zone

resolves https://github.com/fmtlib/fmt/issues/2627