Allow sitebuilder to remove the Summary functionality

Problem/Motivation

For most of my projects, the summary input is unnecessary. It's possible to turn off the summary input off and update the Views to not display summaries. However, the summary still displays on the detail pages of each User Manual entry. Since the summary is empty, it shows the beginning snippet of the content field, which is redundant.

Steps to reproduce

1. Disable the "Summary input" and "Require summary" options on the Content field.
2. Create a new User Manual entry.

Proposed resolution

Update the "Default" formatter on the Content field to only show the data in the field itself.

Remaining tasks

1. ❌ Get maintainer approval of the proposed resolution
2. ❌ Implement proposed resolution
3. ❌ Test

User interface changes

none

API changes

none

Data model changes

none