Explicitly define module position
Style modules currently added through addModuleStyles default
to being in the head ("top" position). This is an unhealthy default,
since only critical styles that are needed at pageload should be
in the head. In order to be able to switch the default to "bottom",
existing module positions have to be defined explicitly.
This change moves 'skins.minerva.icons.images' to the bottom,
as icons don't need to block page rendering. This move soft-depends