fix: dev: convert dnssec system tests to python

Most of the shell-based tests in the `dnssec` system test have been converted to python.  The only exceptions are the test cases that exercised the `dnssec-*` command line tools, and did not interact with a name server; those have been relocated into a new `dnssectools` system test.

Merge branch 'each-convert-dnssec-test' into 'main'

See merge request isc-projects/bind9!10688