Verify: migrate from KeyDB to KiviDB

Use the verify script from the Redis guide. It compares key counts, and each key's type, value and TTL:

Use the verify script from the Redis guide. It compares key counts, and each key's type, value and TTL:

python3 verify.py redis://:$KEYDB_PASSWORD@keydb.internal:6379 \
  redis://:$KIVIDB_PASSWORD@kividb.internal:6380 0 0 1

KeyDB answers HPEXPIRETIME with an error, which the script reads as "no field expiry", and then checks that KiviDB has none either.