Update module dependencies to include views.

I have just noticed something that is goes against the grain, when compare with other contrib modules.

Here is the quote from flag_bookmark.module

This module creates a default Flag and associated views WHEN enabled.

WHEN is my emphasis.

The convention seems to be that when a site maintainer/developer invokes a command like

drush en flag_bookmark

Then the implicit intent is to make sure all associated modules are enabled ... so everything work automatically.

I have listed this as a minor issue, because I can't conceive of having a D8 site without views.
.... maybe someone who turns unused module off for performance....

But it is going to catch that one in a thousand developer...