Messages view on job page needs to use a unique pager id

Problem/Motivation

We display 2 views on that page, the job items and the messages. Currently the job items view incorrectly displays the pager based on the messages view because they have the same pager ID.

D7 should not be affected because it renders the views immediately while D8 relies much more on pre_render/delayed rendering. I also tried to use buildRenderable() on both views but for the messages we need to know the result count as we display it inside a wrapper.

Proposed resolution

Set a different pager id on the second view. This is automatically done on existing sites too.

While doing that, I also improved the view a bit and included the job item column which I think we lost at some point in the 8.x update. I also added support to link to the entity to our EntityLabel views field plugin as well as supporting relationships there.

Conflicts with #2942145: Add method to display job item icon, use it everywhere, so will post a patch when that is resolved.

Remaining tasks

User interface changes

API changes

Data model changes