Portage/Dependency/Normalize.hs: allow CSE for AnyOf style depends

In agda I've notived a problem of lifting such king of depend:
     epic? ( dev-lang/epic
             || ( <hashable-1.2 >=hashable-1.2.1 ) )
    !epic? ( || ( <hashable-1.2 >=hashable-1.2.1 ) )

The patch fixed 'lift_context' to drag AnyOf in upper,
and allows 'propagate_context' CSE for context elements of
arbitrary complexity.

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>