resolvectl: add JSON output support for "resolvectl query"

resolvectl: add JSON output support for "resolvectl query"

It's easy to add. Let's do so.

This only covers record lookups, i.e. with the --type= switch.

The higher level lookups are not covered, I opted instead to print a
message there to use --type= instead.

I am a bit reluctant to defining a new JSON format for the high-level
lookups, hence I figured for now a helpful error is good enough, that
points people to the right use.

Fixes: #29755