While working on internal 64-bit time for BIND 9, the unit test suite for isc_time API has been extended.
Backport the unit tests from 64-bit time branch to the main branch. This should make the unit tests for isc_time API (mostly) complete.
Related to #2959
Merge branch '2959-add-more-time.c-unit-tests' into 'main'
See merge request isc-projects/bind9!5760