Tweak Admin preview / view UX

[esoterik]

Right now the admin sidebar is a bit confusing when it comes to viewing or previewing an action from its edit page:

The preview link shows up in the sidebar as long as the action is saved to the database, but it should really only show up when editing action attributes, and it doesn't work unless you're actively editing the action.

It's also difficult to get to the action page itself from the edit page, so it'd be good to add a view button as well, but in a way so that it's clear what the difference between view and preview is.