Plugins can add to top of body in PUI

[jdshaw]

Allows plugins to add content directly to top of the body of the page in the PUI

Description

Adds another plugin hook to layout to allow plugins to directly add content to the top of the body of PUI pages. Use case example: adding <noscript> content for things like Google Tag Manager.

Related JIRA Ticket or GitHub Issue

How Has This Been Tested?

Local testing Mac OS

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have read the CONTRIBUTING document.
• I have authority to submit this code.
• I have added tests to cover my changes.
• All new and existing tests passed.