Ctools views context

Problem/Motivation

This issue provides a views context plugin as part of #3299868: [meta] Context plugin system → .

Remaining tasks

• We will need a block for every component a view can render.
• Exposed filter.
• Header.
• Text area.
• Footer.
• etc.
• At the moment the views row and pager blocks are only expecting one views context. These need to work when there are multiple views context.