Expose evaluated properties in query results instead of serialized layer definitions

[mourner]

Capturing from #8195:

digging into 5 year commit history around this particular feature (query results including serialized layer), I discovered that the original intent was to return evaluated layout/paint values, not original definitions — see #879. At some point during many refactorings, this changed without anyone noticing.

We could apply a temporary fix to mitigate performance issues, but an ideal solution would be to track down where that change happened, and see if we can avoid full serialization by reverting back to outputting final values of properties evaluated at the time of the query. I'll dig into this further.