[WP][UX] Remove "tabs" for menu local tasks, move into contextual links (and/or admin bar)

"Tabs" (Menu Local Tasks) are a strange UX drupalism (soon to be a backdropism too). Before we had contextual links, tabs made some sort of sense: we needed a way for people to edit things directly from where they are viewing them.

But now we have contextual links, these links allow people to edit all kinds of things directly from where they are viewing them! Let's move the links that are currently displayed as "tabs" into contextual links instead, and see if we can get rid of this concept of Menu Local Tasks.

We have a lot of administrative listings that are currently being displayed as tabs, for convenience. These items would need to be converted into MENU_NORMAL_ITEMS instead. ( IMO, that's what they should have been in the first place, so this will be just a return to normalcy.)