Migrate digdelv dig formatting checks to pytest

Migrate digdelv dig formatting checks to pytest

Move the dig output-formatting and command-line handling checks from
tests.sh into a new tests_dig.py module: +short, +split/+sp,
+unknownformat, reverse lookups, the rrcomments/multi matrix,
+header-only, +ttlunits, +expandaaaa, +bufsize, query-time units and
+yaml timestamp precision, +nocrypto, class CHAOS, query-name error
handling and the UPDATE-opcode rejection.  Repeated checks are
parametrized and the duplicated "+short +rrcomments" check is folded
into a single test.

The shared check_ttl_range helper mirrors the original awk check: it
scans the output line by line, accepts the class tokens IN and CLASS1
(the RFC 3597 unknown-format spelling), and compares the RR type
token textually and the TTL numerically.

Assisted-by: Claude:claude-fable-5