This commit adds optional component and componentId fields to the
preSets variable, which are recorded in the wscache table.
These are then used by (a) core site plugins where a module cmid
is available, and (b) the forum (as an example core implementation)
so that module site plugins and forum provide the new data.
(Note that this is not going to be very useful where we retrieve
data for multiple activities at once, which happens for activities
like Page. Still, it is optional.)
