Improve the user experience of configuring a Maxlength limit.

Problem/Motivation

Our usability tests revealed consistent confusion and unnecessary friction for a user setting a Maxlength limit on a field.

Those issues were:

• "Hard limit" was a more common phrase in mind than "Force truncate"
• The label and explanation of "Safe truncate HTML" was difficult to understand
• Every tester expected HTML tags to be stripped out, not a configuration setting that needed to be enabled. See #3230544: Apply safe truncate HTML behavior by default on rich text fields
• Testers preferred a hard limit to allow a user to exceed the limit when typing in the field and then have the limit enforced when trying to save the form.

Steps to reproduce

Enable the module and navigate to the Manage form display page for the content type you want to set a Maxlength on.

Proposed resolution

1. #3262562: Improve labels, help text and form fields on Maxlength form widget
2. #3259462: Move Summary Maxlength setting above the associated field Maxlength setting.
3. #3230544: Apply safe truncate HTML behavior by default on rich text fields
4. #3262566: Place Maxlength settings inside a field set.