libstdc++: Format %r, %x and %X using locale's time_put facet [PR120648]

libstdc++: Format %r, %x and %X using locale's time_put facet [PR120648]

Similarly to issue reported for %c in PR117214, the format string for locale
specific time (%r, %X) and date (%x) representations may contain specifiers
not accepted by chrono-spec, leading to exception being thrown. This
happened for following conversion specifier and locale combinations:
 * %r, %X for aa_DJ.UTF-8, ar_SA.UTF-8
 * %x for ca_AD.UTF-8, my_MM.UTF-8

This fix follows approach from r15-8490-gc24a1d5, and uses time_put to emit
localized date format. The existing _M_c is reworked to handle all locale
dependent conversion specifies, by accepting them as argument. It is also
renamed to _M_c_r_x_X.

	PR libstdc++/120648

libstdc++-v3/ChangeLog:

	* include/bits/chrono_io.h (__formatter_chrono::_M_format_to):
	Handle %c, %r, %x and %X by passing them to _M_c_r_x_X.
	(__formatter_chrono::_M_c_r_x_X): Reworked from _M_c.
	(__formatter_chrono::_M_c): Renamed into above.
	(__formatter_chrono::_M_r, __formatter_chrono::_M_x)
	(__formatter_chrono::_M_X): Removed.
	* testsuite/std/time/format/pr117214.cc: New tests for %r, %x,
	%X with date, time and durations.