[9.18] chg: dev: Restore the ability to select individual unit tests

This adds the command line arguments: `-d` (debug), `-l` (list tests) and `-t test` (run this test) to the unit tests.

e.g.
```
    % ./rdata_test -t zonemd
    [==========] selected: Running 1 test(s).
    [ RUN      ] zonemd
    [       OK ] zonemd
    [==========] selected: 1 test(s) run.
    [  PASSED  ] 1 test(s).
    %
```

Closes #4579

Backport of MR !9384

Merge branch 'backport-4579-restore-the-ability-to-select-individual-unit-tests-9.18' into 'bind-9.18'

See merge request isc-projects/bind9!9386