Make the default implementation for Asset::actions() return an empty list.
Make the default implementation for Asset::actions() return an empty list.

Returning a disabled action saying "no actions" serves only confusion since
the user cannot do anything about it.

pranavrc/example-gluon,KDE/gluon,KDE/gluon,pranavrc/example-gluon,pranavrc/example-gluon,KDE/gluon,pranavrc/example-gluon,KDE/gluon