fix(profile): adds the prepare hook for the profile page’s owner menu

In 4c94f8809f1131e2d8e073518195b6b65b26aceb the prepare hook was added to
elgg_view_menu, but in the manual rendering on the profile page this hook
was forgotten. This adds it so plugins can reorder/alter the profile
page menus.

Fixes #6085
Merge pull request #7585 from mrclay/6085

fix(profile): adds the prepare hook for the profile page’s owner menu
chore(boot): more formally separate libs are their initializers

engine/lib files now return their own initializer functions which use
injected services.
Merge pull request #7629 from mrclay/lib_inits

chore(boot): more formally separate libs are their initializers