cubicweb #2919287 [facets] start_unfolded is currently static & global: make it more context dependant [open]

For instance, in some table view we would like to start folded while in the general case we want unfolded as a default.

There is no means (that I know of) to make that happen currently.

prioritynormal
typeenhancement
done in<not specified>
load1.000
load left1.000
closed by<not specified>