Portage/Dependency.hs: moved type definitions to 'Portage/Dependency/Types.hs'

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Portage/Dependency.hs: move 'normalize_depend' to 'Portage/Dependency/Normalize.hs'

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