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

test/units/testsuite-75.sh

@@ -821,6 +821,9 @@ run resolvectl reset-statistics --json=pretty
 
 run resolvectl reset-statistics --json=short
 
+test "$(resolvectl --json=short query -t AAAA localhost)" == '{"key":{"class":1,"type":28,"name":"localhost"},"address":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1]}'
+test "$(resolvectl --json=short query -t A localhost)" == '{"key":{"class":1,"type":1,"name":"localhost"},"address":[127,0,0,1]}'
+
 # Check if resolved exits cleanly.
 restart_resolved