Since we cannot have dynamic jump list actions but this is an often requested feature and common
among other desktop environments, at least add the "Places" to entries belonging to a file manager.

To avoid the menu becoming too long, the number of places shown is limited to 5* when the
application is running and the menu would also have window controls. For when it's a launcher,
all places are shown as there the menu is less likely to become massive.

This is added to services that contain the "FileManager" category, such as Dolphin.

*) It actually truncates it to 5 entries only if there's more than 7 places.
There's nothing more frustrating than having a "reveal more" button that ends up adding just one
or two items once clicked.

Differential Revision: https://phabricator.kde.org/D3815