Also fixes:
MDEV-17330 Wrong result for 0 + LEAST(TIME'-10:00:00',TIME'10:00:00')

Problems:

1. These methods did not take into account the current session date flags
and passed date_mode_t(0) to func->get_date():

Type_handler_temporal_result::Item_func_min_max_val_real
Type_handler_temporal_result::Item_func_min_max_val_int
Type_handler_temporal_result::Item_func_min_max_val_decimal

Fixing to pass sql_mode_for_dates(thd) instead of date_mode_t(0).
Note, sql_mode_for_dates(thd) is only needed for DATE/DATETIME
data types. It is not needed for TIME.
So splitting value methods Type_handler_temporal_result::Item_func_min_max_xxx
into individual implementations for
Type_handler_{time|date|datetime|timestamp}_common
and, instead of calling get_date(), reusing inside classes
Time(), Date(), Datetime() and their methods to_longlong().
sql_mode_for_dates(thd) is automatically passed to get_date()
inside Date() and Datetime() constructors.

The switch to classes also fixed the problem reported in MDEV-17330.
Type_handler_temporal_result::Item_func_min_max_val_int() used to
call TIME_to_ulonglong(), which was not correct for TIME.
Changing the code to use Time().to_longlong() solved this.

2. Type_handler_temporal_result::Item_func_min_max_get_date
also did not take into account the current session
date flags in case of conversion from DATE/DATETIME to time
and passed date_mode_t(0) to get_date_native().
Fixing to pass sql_mode_for_dates(thd) in case of conversion
from DATE/DATETIME to TIME.