[regression] Pages Manage Fields, Manage form, Manage display should include name of content type or entity

Problem/Motivation

During the 2015 usability study, users struggled with the process of adding a new content type. After creating a content type, you are redirected to the Manage fields screen; however, the heading for this page does not contain the name of the content type you are managing fields for. It can only be found in the breadcrumb (and even that has issues, see #2513570: Changing name (label) of content type is not reflected in breadcrumb link text).

Consequently, some users thought they failed to create a content type because when they were redirected to the manage fields screen, they said "This page has nothing to do with what I just did."

This is a regression from D7, since that screen uses the content type in the heading.

Proposed resolution

Include the content type name (or entity type name) in the heading of the Manage fields page to orient the user and inform them what they are managing fields for:

Not just for noobies

This will also benefit experienced users because it will help prevent adding fields to the wrong content type.

User interface changes

Manage fields heading will have more text.

API changes

None.

Data model changes

None.

Beta phase evaluation