Meta::ZeroClickInfo: simplify supported attributes check.

Streamline to a single code path for checking key/value pairs.

The hash key look up will be faster than checking against every
element in the array from the function call each time.

On the other hand, even though I got here somehow, I can't actually see
where it will get run.
I considered this.. I also considered ```map { $_ => undef}``` and using an `exists` check instead.  I didn't want to get too fancy just for the heck of it.  For some reason, I thought we might want to toggle them back and forth in development, so I didn't use a map.  Looking back, that probably needlessly complicates things.  I may fix it when I wake up from my long jet-lag nap.